DISTANT SUNS INTRODUCTION The night sky has fascinated mankind for millennia. How many times have you caught yourself gazing upward, wondering which bright "star" that was, setting just after sunset, or what constellation was rising over the neighbor's trees? Let DISTANT SUNS show you. Using a database of over 2200 stars (expandable to 9100 or more) DISTANT SUNS is a powerful tool for acquainting you with the heavens. It will provide you with a more accurate representation of the sky than previously found on personal computers (at least, I like to think so). Indeed, it's power rivals that of a small planetarium where, unhindered by your location on the planet, time of day, or the weather, you can freely explore different parts of the sky. DISTANT SUNS was written to take full advantage of the Amiga's color, graphic interface and processor speed. Simply by pointing and clicking with the mouse, DISTANT SUNS lets you discover a fascinating variety of celestial phenomena - and in the process learn the fundamentals of astronomy. The Universe in "Brief: In the book "Hitchhiker's Guide to the Galaxy", author Douglas Adams sums up the Universe this way: Space is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the [pharmacy], but that's just peanuts to space. And so it is. Consider a light beam traveling at 186,000 miles a second leaving the surface of the sun when your morning alarm-clock rings. It is 6:00 am, Monday, February 8, 1988. By the time you've finally just started to consider rolling out of the sack at 6:08 the beam is sweeping through the orbit of the earth 1 as it heads outward bound towards the edge of the solar-system. After you're done showering, and ready to sit down to a bowl of Rice Krispies it's 6:41, and Jupiter will be catching sight of the ray. It'll be midmorning, 11:12, when the beam sweeps past the orbit of Pluto (and you thought that you had a busy morning!). It won't be until the following Saturday afternoon, 5 1/2 days later, when the beam finally reaches the hypothesized cloud of comets, the "Oort Cloud", said to surround the Solar System, but is only just beginning it's journey beyond infinity. Now you won't have to bother thinking about the ray until the next Presidential election in the fall of 1992. However after all this waiting, the beam has only reached the nearest star next to the sun, Proxima Centuri. In 1994 it reaches Barnard's Star, followed by tiny Wolf 359 just in time for the 1996 Olympics. As you celebrate the turn of the century the beam will be racing by Tau Cetii with a full 20 stars behind it. In the next year it will overcome BD5-1668, L725-32, Kapteyn's Star and Kruger 60A. The sun itself would appear as a rather bland yellowish star slowly receding into the galactic darkness. By the end of the next century, your great-great-grandchildren will be alive as the beam passes beyond the likes of Sharatan, Hamal, Algol and Aldebaran. Likewise it will have overtaken Regulus, Talitha, Miaplacidus and Arcturus. In 2219, the Sun's light would just be reaching the open cluster The Pleiades, in the constellation of Taurus. The Starship Enterprise is just beginning it's 5 year journey into television history. Even after all of this, our journey is still beginning. Now in your imagination, leave this age behind. Leave everything you've ever done, or known, behind. Leave your CD collection behind. Were the beam directed towards the constellation of Sagittarius it would be headed to the center of our galaxy the Milky Way. However it won't reach this point 2 until about the year 32,000 AD. Yet there is still another 50,000 years before the ray can exit the other side of the galaxy. When it does, it will be leaving over 100 billion stars behind. Yet this galaxy is an unremarkable one of unremarkable size with many, many others beyond. And the journey is still beginning. By 200,000 AD the beam will be passing by the Magellanic Clouds in Tucana, satellite galaxies to our own. After this is nothing, nothing for the next 1.8 billion years. Back on earth, we would see the sun as somewhat larger, turning a reddish hue as it slowly burns out. But now, looming ahead is the Andromeda galaxy, our "sister" galaxy and a member of the local group. Looking back towards the Milky Way, you would see a view similar to what the Andromeda galaxy looks like on a fall evening: a fuzzy elliptical patch (although the sight would probably be more impressive). Another couple of million years will finally see this beam escaping our corner of the Universe, travelling out to the open regions of space. Adams said it was big. Now advance again, not another few million years, but a full 20 billion years from the present. The light beam from the sun has at last reached the edge of the known Universe. If the solar system still exists it'll likely be a rather cold and uninviting place, the sun having burned itself out 15 billion years previously. Out here, what the beam would encounter is a giant unknown. Long ago however, scientists were able to see some objects they said were out here, Quasars. But these too remain a mystery as do so many other things. ********** One of the amazing things in the Universe is the range of both times and distances. For instance, in the above example we dealt with distances measured in trillions times trillions of miles. Yet, at the same time, some of the most interesting objects such as black holes or neutron stars may measure only 3 5 to 10 miles in diameter. Or we commonly measure stellar processes in terms of millions of years. Yet there are stars, "Pulsars", which flash 30 times a second! As you can see, the Universe has no shortage of variety. In is my hope that DISTANT SUNS will serve to introduce you to this variety, and perhaps encourage you to explore further on your own. R. Michael Smithwick 4 GETTING STARTED DISTANT SUNS will run on a 512K machine, but barely. If you don't have expanded memory, make sure that no other tasks are running, no Marble Madness, no Bard's Tale, nothing (sorry). This will give DISTANT SUNS the memory it needs, and permit it to shut down the Workbench screen saving an additional 30K*. If you do have extended memory then there should be no problems whatsoever running additional programs. Just make sure that there is at least 380K free. Using the extended data disk will take about another 150K or more. On top of this, I would also recommend using FACC by ASDG when using the point-and-identify option. DISTANT SUNS is started in the traditional fashion by clicking on the icon. When loaded, you will be presented with a quiz question, and the location of the answer in this manual by paragraph and word (paragraph #1 is the first Full paragraph, while paragraph #0 is one split from the previous page). Type in the answer to the question, and press the RETURN key. A correct answer activates the main program. An incorrect response causes the program to prompt you again for the answer. Three incorrect responses and the program returns you to Workbench. You will be presented the entire Northern hemisphere of the sky centered on the North Star, Polaris. DISTANT SUNS is now set to a field-of-view of 180 degrees, with "Planetarium" mode activated. Besides the stars, you'll see the planets as colored points. The sun is the yellow disk, and the moon is the white disk. Over on the right is the control panel which presents status and position information. The menus operate in the usual fashion. When positioned over the stars, the left mouse button may be used to center any point of the sky by simply clicking on that point. 5 In order to see the sky in its full splendor, DISTANT SUNS should be used in a darkened room. Also, some adjustment of your monitor may be necessary to get the full range of stellar brightnesses. When the lights are out you will probably notice that faint scan-lines visible in the "black" background. Vary both brightness and the contrast controls on your monitor so that the scan-lines just vanish. This should place the dimmest stars just slightly above threshold of visibility as they would normally be. Now our journey is just beginning. * You should boot from the DISTANT SUNS disk, and remove any disk from the external drive. If for any reason you should still have any problems, you should try unplugging your external floppy drive (making sure the power is off first). 6 BASIC CONCEPTS It is at this point that we ought to take a brief moment to explore some of the basic concepts of observational astronomy, which will help you in working with DISTANT SUNS. For starters, it is helpful to think of the sky in the same way the early astronomers did -- by imagining the stars and planets are being attached to the inside of a hollow sphere with the Earth at the center. This sphere, in turn, revolves around the Earth, creating the stellar motions. Variations on this theme had each planet on a separate crystalline sphere revolving on its own, which explained their independent movements. But for now, the single sphere model will do. Another concept which is essential for understanding how astronomers describe the various locations of celestial objects is that of coordinate systems. We are all familiar, in one way or another, with coordinate systems. This is a method of specifying the location of a particular place, be it on a piece of paper or the Earth. Our home address, for example, represent one coordinate system, the Earth's latitude and longitude lines are another. In order to pinpoint the location of a star, astronomers have Figure 1. 7 developed their own system for the sky, analogous to the Earth's (fig. 1). The sky's latitude is termed declination, (or dec) and it's longitude, right ascension, (or "RA"). In this "equatorial coordinate system", declination is measured in degrees, as is latitude, and like latitude, ranges from -90 degrees to +90 degrees. Zero degrees declination is called the "celestial equator". Fig. 2 Right ascension, on the other hand, is measured not in degrees, but in hours, minutes and seconds, with each hour being the equivalent of 15 degrees. A second coordinate system that is important is the horizon system, used in specifying the location of an object in your own sky. The two coordinates used are "azimuth", or compass heading, and "altitude", or the angular elevation above the horizon (fig. 2). Both are measured in degrees. And while right ascension increases by motion towards the left, azimuth increases to the right. Because of the Earth's rotation, horizon 8 coordinates of a particular object are constantly changing, while its equatorial coordinates are constant. DISTANT SUNS defaults to using the equatorial coordinate system called "Planetarium Mode", as opposed to your local coordinate system. This was done for two reasons: * Planetarium mode is much faster which makes navigating around the sky all the easier. * Planetarium mode removes the ambiguities introduced by using your local system. That is, Altair's equatorial coordinates are going to always be the same, but its local horizon position changes constantly minute-by-minute. 9 On the right side of the screen is the control panel (fig. 3). This permits you to scroll around through the sky as well as displaying basic status information. At the top of the control panel, you'll find four directional arrows (Fig. 3a) that let you select the scrolling motion of your screen display. Think of these arrows as simply navigational instruments that point you in the direction you wish to move. Move the sky by clicking the left mouse button on any of the arrows. All movement is stopped by clicking a second time on top of the active arrow. The left and right arrows control right ascention (or azimuth when in local mode), and the up/down arrows control the declination (or altitude). Each step is 5 degrees in either direction ("20 minutes" in RA) or 1 degree when the field-of-view is 20 degrees or less. If you look at the extreme northern or southern parts of the sky, where the declination is close to +/-90 degrees, and scroll either right or left, stars will be seen to rotate around some central point. This is caused by the fact that our hollow sphere model rotates on an axis going through the northern and southern points. What you have done, in effect, is 10 to lean back and look up. And what you are seeing are the stars moving around the axis (fig. 4). The point in the Northern sky is marked by the "North Star", Polaris. Figure 4. Coordinates window Beneath the directional arrows is the coordinates window, (fig. 3b), pinpointing the location fo the screen's center. This point may be highlighted by turning on the crosshairs under the Extras menu. If you are in Planetarium mode, the control panel shows you the coordinates in right ascension, measured in hours and minutes, and declination, measured in degrees. For example, at startup the screen is centered on the North Pole with coordinates of 0 hours RA and 90 degrees Declination. In Local mode, the coordinates will be in altitude and azimuth. Zoom Buttons The next items on the panel are the zoom controls (fig. 3c), letting you control the field-of-view ("FOV") as if you had a giant zoom lens. They determine how much of the sky is visible at any one time. With these, you can zoom in for a closer view, or out to see more stars at once. Be aware that the sky refresh slows as the number of objects on the screen increases due to widening the FOV. For large zooms, you may want to use the "FOV" menu item in the Displays menu. 11 Measured in degrees width, a 90 degree FOV means that 45 degrees of the sky is visible on either side of the screen's center (fig. 5). The smaller the field, the larger the images. The smallest FOV is 15 and the largest is 180 which will show you one-half of the entire sky. The most comfortable region is between 40 and 50 degrees. Because DISTANT SUNS is trying to display a 3-dimensional "curved" surface on a flat, 2-dimensional screen, certain distortions will creep in. These are similar to what a wide-angle camera lens might generate. The distortions are most noticeable along the edge of the display while using an FOV greater than 70 or 80 degrees. Their least distortion will be in the center of the screen. Other stuff Below the zoom controls is the rate display (fig. 3d). This tells you what speed DISTANT SUNS' internal clock is running when compared to the real world. Next is the date and time (fig. 3e). Figure 5. 12 The date will be red when the years are AD, and yellow when BC. The last item in the panel is the mode window (fig. 3f). This will remind whether you're in local, landscape, flashcard or planetarium modes. These are selected from the Modes menu item in the Displays menu. 13 MENU CHOICES Now that you've had a chance to checkout DISTANT SUNS' control panel, let's look at the menu choices available to you. The following sections will summarize the options. Additional details will be given in later chapters. (Notice that a number of the menu items have keyboard equivalents, and that some options are mutually exclusive with others. Selecting these will automatically lock out others). Systems Menu Control Panel This will let you open or close the control-panel on the right side of the screen. Free Memory Selecting this will bring up dynamic memory monitor. You may want to check this periodically when using a 512K machine. Quickview Quickview will rapidly set up the display in Local mode, oriented toward any one of the nine directions. The horizon line, and constellation and planetary names will also be switched on. This saves you the time it would otherwise take to turn on everything separately and wait through several screen refreshes. The horizon line indicates where your own horizon is, marking every 5 degrees. The local-altitude option under the "Markers" menu will draw a scale up the center of the screen indicating the altitude in degrees above the horizon. 14 The "up" option will display the entire sky as seen from your location. Remember that because of the wide FOV, the constellations near the edges will be "scrunched up". The display is drawn as if you were outdoors, oriented North, looking up. That way, North would be "below" your chin, or down relative to your face. No Exit is required from Quickview -- just select your options as you normally would. Redraw With the many options that Distant Suns offers it is possible that from time to time various screen elements may trash others. Redraw will simply refresh the entire screen to clean it up if possible. Reset From time to time you may want to turn off all of the objects and identifiers previously loaded onto the screen. Reset will turn off all selected items at once, returning the sky to a plain unadorned state. Settings These options will allow you to set your date, time, location and time-rate. At startup, DISTANT SUNS will read the current date and time from your computer's internal clock. If you haven't set it, you'll need to put in these values yourself. Selecting "environment" will open up a large window showing the current time, location, etc. needed by DISTANT SUNS at startup. You may change any of the values at will by simply clicking on them with either of the mouse buttons. The left button will increase the displayed value, the right will decrease 15 it. A single click of the buttons will change the value by one step, whereas holding down on the button will cause the values to cycle automatically. The longer the button is held, the faster they will change. The "home" and "other" buttons let you keep two sets of location information. One for your home and one for some remote location. Once everything is set, simply click on "save" to preserve the relevant data for use the next time. DISTANT SUNS tries to account for the proper time-zone depending on the supplied longitude. Unfortunately, due to the irregular nature of the zonal boundaries, it is impossible to be sure if the calculated figure is correct. if you are unsure of the required setting, check Appendix E. Moreover, not all countries, states or regions adjust for daylight vs. standard times. DISTANT SUNS always assumes standard time, so check the zone value for this as well. If the longitude is changed to another time-zone, the value will be recalculated for standard time. DISTANT SUNS will allow you to enter any date between 9999 BC and 9999 AD. However, the further you go from the current date, the less accurate the calculations are likely to be. This is due to the many subtle motions in both the earth and stars. Also with this wide of time span, we come across precision limitations with the system's math libraries. Future releases of the Amiga software are expected to correct this. If you make a mistake when changing the parameters, clicking on "reset" will return to the values present when t he window was opened. "Cancel" will cause a reset of the values and close the window, while "ok" will cause the program to make use of the new data. By selecting the rate menu item, you will be able to change the rate for the passage of time. The slider on the rate requester gives you the option of having time stand still, or speed up to 16 100 times normal rates (1 minute of real time will equal 100 minutes of DISTANT SUNS time). The best values fall between 7 and 15 times normal rate. The "real-time" button will select a rate of "1", that is, the sky will update one minute's worth of motion for every minute past. "Freeze" will stop time, setting the rate to "0". The passage of time is most noticeable when DISTANT SUNS is in either Local or Landscape mode, since you will be able to see the daily motion of the sky. You will be able to watch the rising and setting of the stars, sun and moon, and watch the moon move up against the stars. In Planetarium you'll be able to watch the moon's movement through the sky. However, everything else moves so slow by comparison it won't be terribly stimulating. When in Local mode, this is very computationally expensive, so keep the rate to 0 unless you specifically need the motions. When running there will be about a 5 second pause between update calculations to permit access to the menus. Titlebar The Titlebar option will simply turn on or off the screen's titlebar. This is so you may be able to drag down the screen to gain access to other programs. ("Left-Amiga M" will do the same for any program, without having to use the titlebar or depth gadgets). Quit Quits the program (so what else is new?). 17 Display Menu The Display menu controls the major display elements and operation modes. Mode DISTANT SUNS has three main modes for viewing the stars: Flashcard, Local, and Planetarium. Flashcard This is an aid to constellation identification. Selecting Flashcard will turn off any identifiers and position indicators and randomly center a constellation in the screen. Now it is up to you to figure out where you're looking. Clicking on the left mouse button will display the constellation names and viewing direction. After about 5 seconds the system will select another constellation. Local In Local mode, the sky will be displayed as seen from the supplied time and location. Using Quickview under the System menu is the suggested way of entering Local mode to save time spent in setting up the screen. Under this mode, the sky changes from night to night and from one point on Earth to another. Furthermore, the local coordinates of the stars, their altitude and azimuth, will change as the Earth rotates. If you are in the Northern hemisphere you will notice the North Star, Polaris is at an altitude above the Northern horizon equal to your latitude (fig. 6). Were you exactly at the pole, the sky would resemble Planetarium mode. 18 Figure 6. Planetarium In Planetarium (the default) mode, the sky is displayed as if there were no Earth underneath to distort your perspective. This removes any ambiguities that your own location introduces. You will no doubt notice how much slower Local is when compared to Planetarium mode. This is because DISTANT SUNS must do many more calculations in order to shift the perspective to your own frame of reference. And because of this, the stars will be turned off completely for scrolling while in Local (or Landscape) mode. Constellations The names of the constellations may be activated by selecting the "names" option. The same applies for the outlines. Each may be turned off by selecting the item a second time. Take note that generally the names are located away from the center of the constellation so as not to obscure important stars. 19 The 12 constellations of the Zodiac are identified by the yellow names. Deep-Sky "Deep-sky objects" are those non-stellar entities outside of our own solar-system, such as galaxies, star clusters, and so forth. The "Messier" and "NGC" selections will display entries from two of the most popular deep-sky catalogs. The Messier catalog contains 110 entries, and the NGC or "New General Catalog" has over 10,000 listings of which the best 350 are shown here. Since there are so many NGC objects in some areas, the labels only show with a field-of-view less than 25 degrees so as to spread them out a bit. "Legend" opens up a window to aid you in quickly identifying the various types of objects. See the "Deep-sky" chapter for further details. Field-of-View This selection will aid you in quickly moving to a particular field-of-view from 15 to 180 degrees. Identify Identify activates the "point-and-identify" mode which will let you click on top of any object so as to reveal extra information. When activated the pointer will turn into a crosshair. Center the selected star and click the left mouse button. A window will now open displaying information such as the name, magnitude, exact position and sometimes explanatory notes. And in the case of the deep-sky objects, images will be available with the optional data disk. Three sample images are supplied on your disk for "M3", "M57", and "M101". (Refer to Appendix A for 20 their precise location. Be aware that this mode will get confused if there is a an outline nearby. Also, some bright stars may have a dim companion close by, and sometimes this will be detected instead of the brighter star. This will be especially noticeable when using the extended data disk due to the many more stars. A narrow FOV is recommended when using point-and-identify. Refer to the chapter on the stars for explanations of the data fields. Landscape Landscape will turn on an artificial horizon to simulate mountains in the distance. With this activated, your vertical scrolling is limited to a range of +/-20 degrees in altitude. A number of options are turned off when landscape is on, namely constellation outline. Also, Quickview's operations are now modified to quickly aim you around the horizon as before, but it will not automatically turn on the constellation names or horizon line. Lookdown Lookdown will display a view of the solar-system from above. "Inner Planets" will show the orbits from Mercury to Mars. "Middle Planets" covers Earth to Jupiter, while "Outer Planets" will show you Jupiter to Pluto. Since this draws in the main screen it will be erased as soon as the screen is updated. It was done this way for two important reasons: Because it looked neater up against the stars, and having it in a separate window would have clobbered a major portion of the screen. Lookdown will work nicely with the "Tracker" (see under "More Extras" menu) although the outer planets move too slowly to see much action. 21 When the date is changed, the original positions will be highlighted in green so you may compare them with the new positions. Markers The Markers selection will display additional information to aid you in further understanding how the stars are laid out in the heavens. The "ecliptic" denotes the plane of the solar-system based on the earth's own orbit. "Celestial equator" will display the projection of the earth's own equator up against the sky. This is the imaginary line which separates the northern and southern hemispheres of the sky. The "horizon-line", shows you your own horizon projected against the sky. In Local mode, it will be horizontal to the bottom of the screen. It will be 5 degrees above the true horizon in when Landscape is on. In Planetarium you will see the line at an angle because your own point of reference is itself tilted due to your latitude. "Local altitude" will turn on an altitude line when in Local mode. This will show you the altitude above the horizon in degrees. The RA/dec selection will overlay a right-ascension/declination grid on top of the stars, much like the grid in a star atlas. Move Move supplies you two additional ways of moving around the sky: via standard sliders, or more accurately, via the direct numerical input. Right-ascension is entered hh:mm format, and declination in dd:mm (degrees:minutes). Notice that the direct-move window still asks for RA and dec even while you are in Local mode while everything else is in altitude/azimuth. While this is inconsistent, it was left this way to provide you with at least one method of locating objects via RA/dec while 22 in Local, (Since you will rarely be given object coordinates based on your local altitude and azimuth). Names This will turn on the planet names and those of over 75 of the brightest and important navigational start. Search Search will help you locate any of the planets or constellations. With Landscape on, search will respect the +/-20 degree limits on the elevation. If your target is out of range, the azimuth will be correct, but the altitude will be set at the limit. "Search by name" will let you find many of the named objects in the database by simply typing the names in the window. The objects must be loaded into memory for it to work, which means for instance, it will be unable to locate any deep-sky objects unless you have already selected that option. "Search by name" includes a simple wildcard matching scheme. This means that you can type the first part of a name or identifier followed by an asterisk if you don't remember how to spell the entire name. It will search through the loaded lists, and point you towards the first item that it matches. make sure the entry is specific enough to be unique, otherwise if you were to type in "Ursa*" looking for Ursa Minor, it will center on Ursa Major which precedes it in the internal list. Instead you would have type "Ursa Mi*". Currently common names like "Crab Nebula" are not supported. Show Mag This will limit the displayed magnitude. You would probably use this only if you have the extra stars data disk. Until you have found the area of interest, you may not want to take the extra time required to display all of the stars. This option will 23 display only those required for the moment. That is, if you choose "5", only those stars 5th magnitude and brighter will show. Skylight Selecting Skylight will make DISTANT SUNS attempt to duplicate the ambient light generated by cities or towns that wash out dimmer stars. In other words, if you live in downtown Cleveland, the sky will look a great deal different than it would from central Wyoming. In fact, many people find it hard to identify constellations in a country sky because there are just too many stars. Extras Color-Map These selections will change the brightness and colors based on your needs. "Bright" is used to counteract brightly lit rooms which could wash out the screen. This increases the intensity of everything at the cost of narrowing the differences between the brightest and dimmest stars. "Dim" and "red" are used to preserve the "night-vision" of an amateur astronomer who might have his/her Amiga propped up next to the telescope. Night-vision is when your eyes have fully adjusted to the darkness, maximizing their sensitivity. As it takes over 30 minutes to reach this state, astronomers are reluctant to use any lights during an observing session. When necessary, red lights are traditionally used. The "red" selection will turn everything in the display (except the stars) various shades of red. For the most aesthetically oriented observer, the "dim" option was added which preserves the colors, but merely darkens them. "Normal" will return you to the default colormap. 24 Crosshair This activates a central crosshair pinpointing the place indicated by the location in the control panel. Mag Chart This will display a magnitude chart showing the magnitudes by colors instead of intensities. This will show you the magnitude distribution in a clearer fashion. Precession Normally no precession is performed on the stars, since it takes a long time whether it is needed or not. Selecting "auto-process" will cause the stellar data to be updated if the date is changed by more than 200 years. The "stars" option will precess the stars on demand, should you require greater accuracy. Any extra objects such as deep-sky or user data, will also be precessed. So the more you're displaying the longer things will take. Normal precession ignores the outline data. In part a time saving measure, this also permits you to compare the previous stellar positions with the new ones, by using old outlines. See the chapter on the stars for an explanation of precession. Print P&I You may send the point-and-identify data to your printer with this option. However, any Greek characters used in the star's designator's will not show up on the output. Save to IFF You may take IFF screen dumps which can then be loaded into a paint program like DPaint III. You can then add any explanatory text, and optimize the colors for graphics dumps to 25 your printer. Note that the more complex the image (the more stars, etc.) the longer it will take to save. Don't attempt to dump images to the DISTANT SUNS distribution disk, as there is not enough space for even one picture. Sky Images The "sky-images" are what I call the sun and moon. There are two sizes which may be displayed. The smaller ones are correct for a 30 degree FOV, and are used for that and wider scenes. The larger images are correct for a 15 degree view, and are used for 15 to 25 degree views. I added this option for those users of the original ("Classic") DISTANT SUNS (rather, Galileo) who felt that the sun and moon images were too small. "Large" will use the larger images for FOVs up to 100 degrees. "Normal" will return things to their proper perspective. More Extras Star Trails A person's first encounter with astro-photography is usually through the taking of stellar time-exposures with a camera fixed on a tripod. The results will produce streaks, or "star trails" caused by the motion of stars across the field-of-view. This phenomenon may be simulated by going into landscape mode, setting the time rate around 7x, and then enabling this option. Telescope This option will bring up the telescope window. By placing the cursor over any of the planets, the sun or moon, you will be able to see what a small telescope would reveal. 26 Tracker Tracker enables you to follow the motions of the planets through the sky. "Auto-track" will plot the planetary positions for each day, starting from exactly one month before the current date, to one month following. Each blue dot represents a day's worth of motion, and each gold dot, a week. The sun's position will be plotted only at the week boundaries to avoid cluttering up the screen and interfering with the planet's paths. "Manual track" will let you study the motions more closely for the current date, or any other which you may enter into the window. Use the left arrow to advance a day at a time, and the right one will move backwards a day when pressed. The "sun" buttons will turn on the sun's image for daily plotting along with the planets. The moon is not plotted, because it's motion is so great that even a daily plot would be meaningless. If you would like to study lunar motions, just increase the time rate to 30 or 40, sit back and watch. Twilight The twilight mode is meant to simulate daytime. Turning on twilight will do different things depending on what viewing mode you are in. When in Local mode the sky will be a bright blue while the sun is "up". As the sun sets below the horizon, the sky will darken and the stars will begin to emerge. In Planetarium, since the sun is always "up", the sky will be blue all of the time, unless of course, there is a solar-eclipse. User data This option will permit you to construct your own databases to fit your own needs. (see "Creating Your Own Database"). 27 What's Up The "What's Up" window will give you a quick overview of your evening's sky. See the "What's Up?" chapter for further information. Yale Catalog This option will place alongside each star on the screen, the selected data field from the "Yale Bright Star Catalog". one word of warning when using this option: Use a fairly small field-of-view, otherwise the data density could become so great, nothing will be readable. Also, the more stars on the screen, the longer the process will take. An FOV greater than 30 degrees should be avoided when using the standard database, or 15 degrees when using any of the extended databases. "Double stars" will put a "ds" label next to any suspected star. Similarly, "Variable" will flag variable stars with a "var". Over 100 stars have associated comment files with them, so by selecting "comments", highlighted stars will be flagged with a "c". You can then use point-and-identify to read them. See chapter on the stars for more details on what each of the other fields mean. 28 THE PLANETS AND THEIR MOTIONS The planets are believed to be composed of material left over from the formation of the sun. There are two main kinds of planets: the small rocky variety illustrated by mercury, Venus, Earth, Mars and Pluto, and the "gas giants", otherwise known as Jupiter, Saturn, Uranus and Neptune. These are known for their very dense and deep atmospheres and lack of any substantial surface. Jupiter is an especially interesting case in that it has been called a "protostar" due to the fact that it is actually radiating slightly more energy than it receives. if it was slightly more massive it might have evolved into an actual star. (See Appendix C for general planetary data). To the ancient astronomers the planets were called "the wanderers" since they were observed wandering about from evening to evening. Unless one were to observe the planets on a daily basis, their movements might not be noticed. However, if we were to plot their motions over a period of several weeks, we can get an idea of just what the ancients saw. As explained in the Menus section, you can use both the "Tracker" and "Lookdown" features to gain a better grasp of planetary motions. Lookdown will show the solar-system from above, and Tracker will plot the planet's positions up against the stars as seen from Earth. Since both will work together we can perform many interesting experiments. Conjunctions From time to time, the planets will appear to pass very close to each other causing a "conjunction". While they have very little scientific value, the can be quite spectacular. As an example of a fairly recent conjunction, set the date to December 10, 1986, and the FOV to 50 degrees. Now locate the planet Mars using Search. You will notice that Mars and Jupiter are very close together. Turn on "Lookdown/ 29 middle_planets", and look how the two planets are in the same line-of-sight as seen from Earth. Activating Auto-track will show you just how the two planets moved relative to each other. Their closest approach was December 19 (9 dots from the original date). At this time they were a mere 1/2 degree apart. You may want to use Manual-track to get a closer look. Opposition of Mars Most of the time Mars is a relatively unimpressive reddish-orange smudge in smaller telescopes. However, at times of closest approach to Earth, Mars' fine details become visible. Such approaches are called "oppositions". For Mars, September 1988 brought the best opposition during the last quarter of this century. At that time, it was a mere 36 million miles away. First, use the Telescope to view Mars for any date in 1987. During this time, the planet's angular diameter will be no more then 7 seconds (each degree is subdivided into 60 minutes, and each minute, into 60 seconds). Next, set the date to September 25, 1988, and observe again. At this time it will be over 25 seconds in diameter. Use "Lookdown/inner-planets" to verify how close both Earth and Mars really are. Alignments: "The Jupiter Effect" Another "event" regarding the positions of the planets has to do with the so-called "Jupiter Effect" of several years ago. Every great while, the planets will be aligned in a narrow range of the sky. In the past, such alignments were believed to result in great world catastrophies, causing global panic. A recent throwback to that happened in early 1982, when all of the planets were visible in almost the same quadrant of the sky. For years before that time, a popular book called The Jupiter Effect, claimed that this would trigger all sorts of natural disasters 30 culminating in a major California earthquake. This was supposed to be the result of the cumulative effect of the planets' gravity pulling on one side of the earth. You can observe this alignment by setting the date to March 10, 1982, and opening the FOV to 90 degrees. Place Jupiter in the center of the screen. By turning on the planets' names, you will notice six of the eight planets are within the same 90 degree quadrant. Opening up to 180 degrees will reveal Venus and Mercury about 45 degrees to the left of Neptune. Now, turn on Lookdown for the 3 different settings, and you will see that if this was an alignment, it was marginal at best. Needless to say, California is still here, and a couple of authors got rich. Another more recent alignment dealt with the four outer-planets: Saturn to Neptune. Set the date to September, 1987, and you will see that indeed, they are in the same general area of the sky. This phenomenon played an important part in the so-called "harmonic convergence", which had hordes of believers heading towards the mountain tops to usher in the so-called "New Age". Retrograde Motion Another exercise regarding planetary pathways is to study the motions of Venus and Mercury. Up until the time of the astronomer Copernicus, common belief maintained that the Earth was the center of the Universe with the Sun, Moon, planets and stars all orbiting around it. Unfortunately, a few inconsistencies crept in to upset this idyllic viewpoint. For example, the planets would, on occasion, slow up and of all things, move backwards. In an effort to explain this phenomenon, the astronomers of the day invented "epicycles" which forced the hapless orbs into making a small orbit on top of their main orbits, causing them to back up every so often. This still did not explain all of the movements, so more epicycles were stacked on top of the 31 earlier ones, (fig. 7 & 8). Eventually, some planets collected up to 14 levels of epicycles, but still refused to behave. We can see this mysterious behavior (now called "retrograde motion") by observing Venus and Mercury. Figures 7 & 8. Set the date to December 10, 1986, center Mercury in the middle of the screen, and the FOV to 60 degrees. Venus should be over at the right-hand side. Turn on the inner-planets Lookdown, view, and the planet names. Now start Auto-track. You should notice a pair of rather unusual plots. The Lookdown view should help explain what is happening: Our own point of reference on the Earth is moving at different rates from Venus and Mercury. In fig. 9a, Venus will be seen to be moving in roughly a straight line. However, in fig. 9b, Venus curves around the edge of it's orbit as seen from Earth, causing the apparent reverse in motion. Another fine example of this can be seen by setting the date to September 1, 1990. Center Mercury in the screen, and turn on Auto-track as before. no wonder the ancient astronomers were confused! 32 Figure 9. Orbital Speeds By now, you may have noticed that some planets move faster than others. This is due to many reasons. One is that the farther a planet is from the Sun, the slower it must travel to remain in orbit. You may easily observe this by comparing the relative orbital speeds of the inner planets. Activate "Lookdown/inner-planets", then Auto-track. Now watch Mercury, Venus and Earth race each other around the Sun. Planetary Eclipses One of the rarest forms of eclipses is when one planet actually moves in front of another. One such eclipse occurred on January 19, 1591, when Mars passed in front of Jupiter. Set your location to a latitude of 48 degrees N, and a longitude of 7 degrees E (near Stuttgart, Germany, where astronomer Johannes Kepler recorded this event). The time-zone is -1, and local time, 7:00 am. After searching for Jupiter, you'll notice both Mars and Jupiter are in the same 33 location. Activate the telescope and look at this more closely. Using Manual-track, you can investigate their motions more precisely. Planetary Phases The moon is not the only object int he sky to exhibit phases - Venus and Mercury will show them as well. Set the date to January 1, 1987 and locate Venus. Now observe it with the telescope. You will see a crescent phase, looking much like a tiny moon, indicating that it is on our side of the Sun (fig. 10a). Advance the date to March 1. Venus will look like a first-quarter moon, and will be somewhat smaller as it moves away from the earth (fig. 10b). Once again, advance the date ahead to June 1, 1987. This time as Venus sweeps around toward the opposite side of the Sun you will see it as a "givvous", or near full phase. Figure 10. 34 Which is the furthest planet? No doubt, you grew up learning that the furthest planet from the Sun was Pluto. Not so, at least right now. Pluto's orbit is the most eccentric and most highly inclined of any of the planets. For this reason, Pluto crossed inside the orbit of Neptune in 1980, and will remain so until 1999. You can see this by using lookdown on the outer planets. Stellar occultations On July 7, 1959 a very rare event took place, when the planet Venus occulted the star Regulus. This is the only time Venus will eclipse a first magnitude star for several hundred years. Use Galileo to take a look at this by setting the date as mentioned above. Next select the "stars" option in the "Precession" sub-menu. Search for Venus, and you should notice Regulus extremely close by. Since the planet moves so fast, you'll need to juggle the time around to find the actual time of occulation for your area. Ecliptic Imagine a flat surface extending out from the sun through the Earth, heading out towards infinity. This forms the plane of the solar-system. Now when projected up against the sky it si known as the "ecliptic". Turn on the "ecliptic" (in the Display menu) along with the names of the planets. You will quickly notice that each of the planets, (including the sun) will roughly follow the ecliptic through the sky. The planet Uranus is closest to the ecliptic, being inclined only 3/4ths of a degree, while Pluto in its eccentric orbit is tilted a whopping 17 degrees. (See Appendix C for the inclinations of the other planets.) 35 STARS DISTANT SUNS uses as its primary database, the "Yale Bright Star Catalog". This is one of the most popular and commonly used databases for astronomical software. The database on the main disk contains 2200 stars down to magnitude 5.25. You can access the entire Yale catalog of 9100 stars, with one of the extended data-disks available separately. Using either point-and-identify, or the More-Extras/Yale catalog option, you can access many of the following extra data fields supplied with the database. Magnitudes The brightness of a star of other object in the sky is given by a value called magnitude. The lower the magnitude, the brighter the object, and vice versa. Each magnitude represents an intensity of about 2.5 times less than the next lower value. The dimmest stars visible to the unaided eye are about magnitude 6.5. This means that under the best stargazing conditions, approximately 3000 stars can be seen from horizon to horizon out of a possible 6000 stars. it would make sense that the brightest stars would be magnitude 0, but when measurements of stellar brightnesses were refined, it became necessary to indicate even greater luminosity. Thus, some of the brightest objects are actually given negative magnitudes. For example, the sun blazes away at a magnitude of -26.3, while the next brightest star, Sirius, shines at -1.46. B-V "B-V" (pronounced "B minus V") color is an index of the actual color of the star. The hotter, bluer stars will be negative values, and the redder, cooler stars will be positive. The range will be from -.5 to 2.0 with 0.0 being pure white. 36 Double Stars Frequently, what looks to be a single star may be resolved into two or more stars through a telescope. These are commonly called "double stars" or "binary star systems" (although many are actually multiple systems containing several stars). "Physical" doubles are those which form an actual system, orbiting around some common gravitational center. "Optical" doubles are two stars which happen to be along the same line of sight. The orbital periods of binaries may go all the way from a matter of a few days, on up to several thousands of years or more. Unfortunately, the faster period binaries must be so close to each other, they cannot be seen with the human eye. Such systems are usually detectable via spectroscopic means, hence the name: "spectroscopic binaries". And in many cases the stars may actually be so close as to be physically touching each other. Although most double-stars have periods much too long to observe any motion, a few are short enough to show movement within the lifetime of the average astronomer. Some of the more well known double-stars would include Polaris (the North Star) and Sirius (the brightest star, in Canis Major). Mizar, the bend in the Big Dipper's handle, is perhaps the best known double-star and is easily visible with DISTANT SUNS. With a period of several thousand years, this star is said to have been used as an eye test by American Indians. The "double-star" selection on the Yale menu will flag any multiple stars with a "ds". Using point-and-identify you can bring up further information about the double. The first number tells the angular separation between the furthest components in arcsecs, and the second value is the difference in magnitudes between the two brightest members of the system. 37 Names Each star will have a minimum of several different designators. DISTANT SUNS supplies up to four of these. The brightest stars have proper names, handed down to us through thousands of years of tradition and myth. A somewhat more practical method was developed in 1603, in which the main stars in each constellation were assigned a Greek letter. In general the brightest star was termed "Alpha", the next brightest, "Beta", and so on. Since then, numerous other cataloging systems have been developed usually to classify the stars according to some specific characteristic. DISTANT SUNS supplies two catalog id numbers, the Yale and one for the Henry Draper ("HD" number) catalog. By the way, all of the star comment files are keyed to the HD number. So if you would like to create your own, simply name it with the HD number followed by ".etxt" and place it in the directory "data/pidat/pietxt". Variable Stars Another class of stars is the "variable" which actually change brightness over time. There are two main varieties: "binary variables" and "physical variables". The binaries are nothing more than double-star systems mentioned above which we Figure 11. 38 vie edge on. The variations in brightness is therefore caused when one star eclipses the other. Such variables will have long steady light curves with short dips every few days (fig. 11). Physical variables fluctuate by some not clearly understood physical process. Variety is something which variables find no shortage of. Some vary with a precise regular period, while others behave erratically. Many will change several magnitudes in brightness, while others may change only a few 100ths of a magnitude. Some will have long periods of several years, others, a few hundredths of a second, (as in the case of pulsars). And one variety, the "nova", varies it's brightness by exploding. (The Supernova of 1987, in a matter of only hours released 1000 times the amount of energy of the sun over it's entire 10 billion year lifespan). One particular kind of variable that has become very useful is the "cepheid" variety, of which about 500 examples are known. Cepheids are unusual in that their fluctuations follow a very precise set of rules. The most notable being that there is a close relationship between the period and luminosity of the stars. Knowing the period, you can determine the luminosity, and knowing the luminosity you can determine the distance when compared to their visual magnitude. Using this method astronomers are able to determine the distances to nearby galaxies. Pulsars are one of the most interesting variable stars. The first one discovered in 1968 by the Cambridge university Observatory, had a period of a mere 1.337 seconds. An amazing amount of time when most processes in the universe are measured in terms of thousands to millions of years. Another pulsar discovered later, know as 'Tau X-1" has a period of only .033 seconds! The current theories have pulsars being "neutron" stars, rotating very rapidly. Their energy is focused by a strong magnetic field into a strong beam, and is directed outward along the rotational equator, much like a lighthouse. Each time a beam crosses our path, we receive a 39 flash. The precision of pulsar flashes had astronomers first thinking that they had discovered an artifact from some alien civilization. Stellar Classes Ia. Most Luminous Supergiants Ib. Least Luminous Supergiants II. Bright Giants III. Normal Giants IV. Subgiants V. Main Sequence VI. Subdwarfs Table 1. Stars are most commonly subdivided into many different classes by their chemical makeup as derived by their spectra. The spectra is the "finger print' of a star, and is revealed using a "spectroscope". A stellar spectra looks like the rainbow band of light that a common prism reveals when placed in the sunlight. By spreading out this band, dark "absorption" lines are revealed which are caused by different chemical elements in the star absorbing a particular color. Therefore helium will show up as one set of bands, and hydrogen as another set. Figure 12 illustrates the distribution of the stars in terms of luminosity vs. spectral class. This is the famous "H-R" (Hertzsprung-Russell) diagram, developed in 1913. The strong central band is called the "main sequence" as it describes about 90% of all stars. The Sun would be in almost the exact center of the chart. In upper right are the "red giant" stars, large cool dudes several hundred times the size of the sun. Stretching across the top are the massive "supergiant" stars which may be as much as 50,000 times as luminous as the Sun, such as Rigel in Orion. In the lower left-hand corner belongs to very hot, small stars such as "white dwarfs". 40 Hertzsprung-Russell Diagram Figure 12. 41 TABLE 2 THE CHIEF SPECTRAL CLASSES O Very hot (35,000 K) blue-white stars with large mass and high luminosity. Spectral lines include ionized helium, nitrogen, oxygen, and hydrogen. Lambda Orionis, Zeta Puppis are O type stars. B Hot (20,000 K) blue-white stars with large mass. Spectral lines include prominent helium bands with highest intensity at B2 and disappearing at AO. Alpha Eridani, Rigal, Spica and Regulas are B type stars. A Hot (10,000 K) white stars with luminosities 50 to 100 times that of the sun. Spectral lines contain strong bands of hydrogen, while helium is missing. Altair, Sirius and Vega are A type stars. F Warm (7000 K) yellow-white stars. Strong calcium lines in spectrum with other metals present, and weaker hydrogen lines. Alpha Persei, Procyon and Canopus are F type stars. G Warm (6000 K) yellow stars. Metals are prominent in spectrum, with weaker hydrogen lines. The Sun, Alpha Centauri, and Capella are G type stars. K Warm (4000 K - 4700 K) orange stars. The spectrum contains many strong metal lines, weak hydrogen lines, and the appearance of hydrocarbon lines. Alpha Ursa Majoris, Pollux and Arcturus are K type stars. M Cooler (2500 K - 3000 K) red stars. Wide spectral bands from titanium oxide, with many other strong metallic lines. Many show bright hydrogen lines. Betelgeuse, Mira and Antares are type M stars. N Deep red cool (2500 K) giants. Carbon spectral lines appear. Mostly variable stars, Y Canum Venaticorum, R Leporis and S Cephei are type N stars. R Orange red stars similar to type N, but warmer. Carbon bands are weaker. may be path through which type G became type N. RU Virginis and S Camelopardi are type R stars. S Red stars similar to type M but with zirconium oxide bands replacing titanium oxide. Complex spectra, usually variable, with hydrogen emission lines. R Cygni is a type S star. W Hot (50,000 K+) blue giants, known as Wolf-Rayet stars. High luminosities, similar to type O but with expanding gaseous shell and extremely turbulent atmosphere. Gamma Velorum is a type W star. 42 The letters O, B, A, F, G, K and M are used to identify the main classes (table 2). Finer distinctions are marked by the numbers 0 to 9 following the letter. For instance, our Sun is spectral class G2, or Rigel is B8. Still finer classifications are required due to differences in luminosities within a particular spectral type. These are given by the "MK" identifiers shown in Table 1. Therefore the complete class of the Sun is G2 V, while Rigel is B8 Ia. Stellar Motions While they appear unmoving to us, the stars along with everything else, never stand still. The two kinds of stellar motions DISTANT SUNS deals with are "radial velocity" (speed coming towards or going away from us) and "proper motion" (movement against a fixed background). Radial velocity, measured in kilometers/second, is determined from the star's all important spectra. As a star varies its distance to us, the "doppler effect" takes hold and shifts the spectral lines mentioned above. If a star is receding, or going away from us, the lines are shifted towards the red end of the spectrum. If it is approaching us, the lines move towards the violet end, hence the name "Red Shift". The red shift has indicated that the entire Universe is expanding, much like spots do on the surface of an inflating balloon. On the other hand is proper motion. This is measured in arc-seconds/year of angular motion up against "fixed" objects in the sky. Naturally, the closest stars would be seen to have the fastest proper motions. Barnard's Star (the 3rd closest star at 6 light years) in Ophiuchus is the champ. It can be as easily seen zipping through the heavens at the breakneck speed of 1 degree every 351 years. There is yet another motion, called precession, which has the unfortunate effect of making all star atlases of the world obsolete every 100 years or so. This phenomenon is a subtle 43 motion, or wobble of the Earth's axis, where one "wob" takes some 25,800 years. All stellar positions will gradually shift as a result of this. That is why stellar data is prefaced by the "epoch", or the year for which it is most valid. For instance, DISTANT SUNS' database is epoch 2000, meaning that the positions of the stars are correct for the year 2000 AD. This doesn't make the data useless for the current year, since the motions are so slow, new epochs are calculated only every 50 years or so. One by-product of precession is that our current North Star, Polaris, is only temporary. In the year 4145 AD, the star Gamma Cephei will hold the honors. DISTANT SUNS can demonstrate this with the precession option in the Extras menu. "Auto-precess" will cause the epoch to be recalculated for every 200 years change in the date. The default is off. This was done since it takes a long time to recalculate to new positions, so I didn't want to waste the time doing so if it really wasn't needed. "Stars" will precess the stars on demand, should you want resolution finer than the 200 year boundary. "Outlines" will precess the constellation outlines on demand. This saves the time it would take in recalculating the outlines if all you wanted to do is to look at the new stellar positions. Also, by not precessing the outlines automatically you can do a "before and after" look at the sky in one shot. Try this by centering Polaris and setting the FOV to about 60 degrees. Turn on auto-precess and set the year to 4145 AD as mentioned above. When the new positions are recalculated, and stars refreshed, turn on the outlines. What is wrong with this picture? There aren't any stars marking the ends of the lines. You should be able to make out the outline for the Little Dipper where it used to be, with the end of the handle pointing out Polaris's former location. Nearby is Gamma Cephei, (use "identify" to verify this). Now precess the outlines, and things should begin to look normal. Another more obvious motion of the stars is caused by the rotation of the earth. If you were to take a time exposure of the night sky with the camera aimed towards Polaris you would get 44 a picture of streaks, or "star-trails" circling around the star. Since Polaris represents the northern "axis" of our hollow sphere model of the Universe, it's apparent that the stars should appear to rotate around this point. You can see this for yourself by going into Landscape mode and setting the time rate to about 7x. Turn on the Star-trails option to simulate time exposures. Now sit back and watch. 45 DEEP SKY OBJECTS "Deep-sky" objects are non-stellar objects outside of our solar-system. These include such things as star-clusters, galaxies and nebulas. Star Clusters Star clusters are groupings of stars which are gravitationally dependent on each other. Open clusters are loosely formed collections. The pleiades (M45 in Taurus) or the Hyadies (the head of Taurus), are fine examples of these. In some cases open clusters might contain fewer than a dozen stars. On the other hand there are "globular clusters", which are very tight spherical formations containing hundreds of thousands of stars. "M13" in Hercules is one of the most notable examples of this. Since star clusters are a part of our own galaxy, they will make the regions of the Milky Way. As a demonstration of this, open the FOV in DISTANT SUNS to 180 degrees for a fish-eye view of the Universe. Center Scorpius, and turn on the NGC objects. You will notice the globular and open star clusters (green and red points) localized along a particular strip of the sky. This is where you would see the Milky Way on a dark night. The region over at the far right is above the plane of the galaxy. Without the Milky Way to block the rest of the universe, you will see a heavy concentration of galaxies over on the edge of the view. Now center this and you'll be looking straight into the middle of the Virgo galactic cluster. Over on the lower right-hand side of the screen you will see a gathering of open-clusters. Once again, you're back into the Milky Way, looking away from the center into one of the spiral arms. And once again, the outside galaxies are blocked from view. One can only wonder what spectacular views lie on the other side that we shall never see. 46 Galaxies Galaxies are often referred to as "cities of stars", the most famous being our own Milky Way. Galaxies typically play host to billions of stars. Galaxies such as the Milky Way or the Andromeda Galaxy (M31) are classified as "spiral" because of their strong disk-shaped appearance (fig. 13a). Many spirals in fact show distinct arms curving out from the core, looking much like a giant celestial whirlpool. Elliptical galaxi0es are those which have no strong disk but still maintain a rounded form. (fig. 13b). Irregular galaxies have no form whatsoever (fig. 13c). The Small Magellenic Cloud in the Southern skies is an example of one of these. Figure 13. Nebula Nebulas are interstellar dust and gas clouds which provide raw materials for new stars. It is believed that over a third of our galaxy's mass is in this form. The most well-known nebula is the remarkably beautiful M42 in the constellation of Orion. This is called a "diffuse nebula" because of its loose irregular shape. Planetary nebulas are those which have a rounded planet-like appearance. These usually result from a star which at one time became unstable and exploded (a nova), shedding it's outer layers. The Ring Nebula in Lyra (M57) and Rosette Nebula in Monoceros (NGC2237) are fine examples of such objects. 47 Visible in even the smallest telescopes, the Ring Nebula looks like an intergalactic smoke ring blown there perhaps by a relaxing deity. Nebulas may either be dark or bright. The dark ones, such as the famous Horsehead Nebula in Orion, look much like "holes in the sky", obscuring everything behind them. This is because they simply have no stars near enough to illuminate them. For this reason, some feel that the dark nebulas represent the original matter left over from the creation of the Universe. On the other hand, the bright nebulas frequently have been called "stellar nurseries". In the center of the 30 light-year wide Orion Nebula for instance, objects have been observed which are believed to be stars in the actual process of forming. Nebulas are typically composed of hydrogen and helium, with traces of carbon, oxygen and nitrogen. Deep-Sky Catalogs DISTANT SUNS makes use of two of the main deep-sky catalogs. The first one is called the "Messier Catalog" after the French astronomer Charles Messier, and contains 110 entries. Compiled in 1781, the catalog was developed as an aid to comet hunters who might mistake the faint smudge of a galaxy or nebula for a comet. Obviously this listing contains the most famous objects in the Northern skies. The other set of objects belong to the New General Catalog, NGC, which comprises over 10,000 entries. DISTANT SUNS will display the best 340 of these (see Appendix B0. Because the long NGC catalog numbers could interfere with each other with wider FOVs, they aren't drawn until it is less than 30 degrees. Otherwise the objects will be shown merely as color-coded pinpoints. 48 WHAT'S UP? The "What's Up?" screen will present you with a quick overview of the evening's sky (fig. 14). At the top you will find the date read from the Amiga's internal clock ("today's date"), the date you've set using DISTANT SUNS' date/time requestor ("display date"), and the number of days from t he start of the year ("day"). Figure 14. Also at the top is the "Julian date". This is the number of days from the "fundamental epoch" of Greenwich noon, January 1, 4713 BC. With the vagaries of traditional calenders, and the need for precise calculations, the Julian date enables astronomers to establish exact times for particular events. Within DISTANT SUNS every date is converted to the Julian date before a calculation can be done. 49 The status of the planets is shown in the center of the screen. The color of the planet's name will tell you approximately what time it will be visible. Red planets are for the lazy observer, as they are observable before midnight. Yellow planets are for the more hardy observer, since they are only visible between local midnight and dawn. The blue planets are not visible at all during the nighttime hours. More precise information may be retrieved by clicking on the planet's symbol, opening up an additional window (fig. 15). As to be expected, you are given the coordinates and rise/set times. You are also given the distance to the planet in both "astronomical units" and "light distance". An astronomical unit ("AU") is 93,000,000 miles, the approximate distance from the Earth to the Sun, and is commonly used in giving distances within the solar system. Light distance measures the length of time required for light or (radio signals) to travel from the Earth to the planet. The light distance plays an important part in how spacecraft such as Voyager or Galileo are controlled. For instance, when Voyager flew by Neptune in August, 1989, it took radio signals over four hours to reach it. This meant that if something in the spacecraft needed to be activated by ground control, it would take eight hours to find out whether the spacecraft did as commanded. 50 Immediately below the planets are the rise/set times of the Sun and moon. To the right of this block is an image showing the current lunar phase. A moon which is getting larger in size is said to be "waxing" until it is full. After that, it is "waning". (See the chapter on the Moon for more details). At the bottom of the screen is information about upcoming meteor showers. By clicking on the symbol, you'll see further information about the upcoming shower. (See the chapter on Meteors). The last item in the screen are rise/set times for the constellations. Not all constellations are visible from every point on the earth however. 51 METEORS DISTANT SUNS will keep track of the next meteor shower for you by use of the meteor button in the What's Up window. Meteors are small solid particles in orbit around the Sun and, in many cases, believed to be debris left by passing comets. For this reason meteors tend to be grouped together in comet-like orbits and often have been linked to known comets. It is when the Earth passes through one of these streams that a meteor shower occurs as the particles burn up in our atmosphere. On any night, the average observer should be able to see about five "stray" meteors per hour. The typical shower will generally triple that rate while the best ones (such as the Persieds of August and Geminids in December) may have 50 or more (see Appendix E). The distribution of meteors along their orbits is not uniform. Therefore, what may have been a bland shower one year might be a memorable event the next. The most notable shower of this sort is the Leonids of November. Usually the Leonids produce about 15 or 20 streakers an hour. But early one morning in November 1966, along the Western coast of the United States, rates approaching one-hundred fifty-thousand per hour were reported. This was a repeat of the famous 1833 shower which prompted one 19th century writer to exclaim: "Never did rain fall much thicker than the meteors fell to the Earth...". Occasionally, meteors the size of small rocks will join the fray, producing what is called a fireball. The bigger ones may be seen to break apart forming two or more fiery trails. The biggest of these might survive their entry and strike the Earth. These meteors then become known as meteorites. The mile wide Barranger Crater in Arizona is a dramatic example of this. The names of the showers are derived from the area of the sky from which the meteors appear to radiate (hence the name 52 "radiant"), like spokes in a wheel. Therefore the Leonids would appear to be coming from the constellation of Leo. The best time to observe a shower is after about 2:00 AM local time until dawn. Since the meteors can appear in any part of the sky, a telescope or pair of binoculars would only hinder the viewing. 53 SUN AND THE MOON Without a doubt, the two most prominent objects in the sky are the sun and the moon. In the past they were seen as gods to be appeased or celestial lovers to write stories about. Their influence on our lives is obvious. From control of the tides, seasons, to weather patterns, nearly everything we do can be tied to the sun and to a lesser degree, the moon. Sun [WARNING: If you value your eyesight, don't ever look directly at the sun without the aid of a specially equipped telescope!] When we talk of the stars, most will think of the night and the scintillating pinpoints of light scattered across the sky. But the sun is also one of the pinpoints, just a whole lot closer. An unremarkable star, of average size (800,000 miles in diameter), the sun provides us a closeup opportunity to study stellar processes. The "surface" of the sun is approximately 10000 degrees (as compared to the interior which can reach millions of degrees!). Sunspots are compact regions which are cooler, dipping down to a brisk 7000 degrees. These are areas currently going through intense magnetic disturbances. There is usually a lighter fringe called the "penumbra" surrounding a darker core, or "umbra". Since the sun rotates in about 27 days, it is possible to observe the spots travel across the disk, disappear, then return days later (if they haven't vanished from the surface). Sunspot activity follows an 11 year cycle. As of this writing, we've just started cycle 22, which will peak around 1991. During the cycle minimum, days may go by with no spots visible at all, whereas at the peak, dozens of patches may be seen. Using DISTANT SUNS' telescope, you may see what sunspots look like. Unfortunately, the image is static so don't expect to see things change. 54 The activity causing sunspots directly affects the physical properties of our atmosphere. It is responsible for the aurora ("Northern" or "Southern" lights), and for the way radio waves travel around the world. Shortwave listeners are familiar with the phenomenon of how on some days their favorite radio station may be strong, and on others, it might not be audible at all. You may observe sunspots directly only through the use of specifically modified telescopes. And then, only with filters placed over the end of the scope, and not the eyepiece. For amateur telescopes, use a "reflective" filter, as opposed to the absorbtion variety ("smoked glass") which can still pass dangerous invisible UV and infrared light. Midnight Sun The maximum altitude that the sun reaches in the sky is based on two things: 1) the latitude of your location and 2) the tilt of the earth's axis. By changing the latitude in DISTANT SUNS, you will notice how the sun's altitude varies, the closer to the equator the higher it is and vice-versa. It is the earth's tilt that can produce one of the more disorienting phenomenona: that of the "midnight sun". For instance, during the summer, the sun never sets for any observers within 23 degrees of the North pole, but instead travels in a loop just above the horizon. What has happened is that the observer has moved out of the region that can be shaded by the earth in it's rotation to a part that cannot be shaded (fig. 16). Figure 16. 55 You can use DISTANT SUNS to demonstrate this by setting the latitude to 67 degrees (23 degrees away from the North Pole), and the date and time to June 20 (the first day of summer) at 12:01 am. Now go into Landscape mode, and search for the sun. You should see it above the horizon (if you can't see it, the mountains might be in the way, so go over to local mode and tun on the horizon line). Now turn up the time-rate to 50x or more, and you'll see the sun skirt around the horizon going from 0 degrees to 23 degrees in altitude. Solar Eclipses One of the most beautiful and rarest of all celestial events is the solar eclipse. A solar eclipse occurs whenever the Moon passes between the Sun and the Earth, casting its shadow onto the surface of the Earth. DISTANT SUNS can be used to reproduce recent eclipses. The last total solar eclipse to happen over the mainland United States took place on the morning of February 26, 1979. If you want to "see" this particular eclipse, set the location to 117 degrees W. longitude, 46 degrees North latitude, and the time-zone to +8.0 hours. Now set the FOV to 30 degrees and the time to 7:00 AM. Search for the Sun. You should see the new Moon slightly to the lower right of the Sun. Change the time to 7:30 and you'll notice the Moon just beginning to cover up the Sun. Change the time to 8:25, and you should now be at totality. I would recommend going to see an eclipse in person. One of the unfortunate facts about solar eclipses is that the pathway of the lunar shadow is so narrow, being no more than 80 or 100 miles wide. Totality lasts from only a few seconds to a maximum of 7 min 40 sec. The best way to see one for a 56 novice would be to go in a package deal. Such "Eclipse tours" are commonly advertised in the astronomy magazines. there are between two and five solar eclipses per year, and each is preceded or followed by a lunar eclipse. Moon Orbiting around the Earth at an approximate distance of 250,000 miles is the Moon. With a diameter of about 2100 miles, over 1/4 that of the Earth, the Earth-Moon system has sometimes been called "twin-planets". The Moon orbits the earth with a period of 27.3 days, the same length as its day. As a result of this, it always keeps the same face towards the earth. The origins of the Moon are still shrouded in mystery. Some feel that it might have formed with the Earth, others think that it was "captured" by the Earth when it got too close. No matter where it came from, the Moon easily provides one of the most dramatic views through any telescope or even a pair of binoculars. The rough jagged mountain ranges bordering the smooth Maria, or "Seas", provide a stunning sight when lit from the side. Craters within craters, lava flows, and the lunar "rilles" (lava "river beds") may be seen through even the simplest of telescopes. As a result of its orbiting around us, the Moon exhibits the familiar phases. when it is growing in size, it is said to be "waxing" until it is full. After that it is "waning". The phases are created by the varying angles at which we see the Moon. That is, if the Moon is to our side in its orbit, we will see one half of its face illuminated. If it is near to the Sun, we are in effect, behind it, and so will see no part of it illuminated (fig. 17). DISTANT SUNS' telescope will show you approximately what you would see through a small amateur instrument. Of course, a lot of the sharpness is lost because of the monitor's resolution, but you should get an idea of what it is like. 57 Figure 17. You may be wondering why we don't get an eclipse every time the moon is new. The plane of the Moon's orbit is not exactly in line with the Earth's, but is in fact tilted about 5 degrees. The two intersection points of the plane with the Earth's are called "nodes". When the new moon is near either one of these points, it will be in line with the sun and therefore create an eclipse, otherwise it will be too far above or below to block the Sun. 58 CREATING YOUR OWN DATABASE DISTANT SUNS is an open-ended package in that it will let you expand the database to suit your own needs. When done, the "User Objects" feature in the More Extras menu may be used to display them or not. Data is entered using an editor such as "ed", or "emacs" which is supplied on the Extras disk that came with your machine. This feature might be used to add in variable stars should you be a member of the AAVSO. Or if a new comet is discovered the weekly positions could be entered in from data published in a magazine or newspaper. You are provided with a sample file located the in the directory :data/userdata and called "ud_stellar.dat". A sample entry might look like 2 1445.3 9.98 2 OQ172 The "2" is a unique serial index number, beginning with "0" and going on up to 499, for a total of 500 objects. The next number, 1445.3, is the Right Ascension in the format of hh:mm.mm. so this object is at an RA of 14 hours, 45.3 minutes. Next is the declination in decimal degrees. The "2" is the color of the object. The last field, "OQ172", is the label which will show up when the objects are activated. The label is limited to 25 characters in length. The colors are: 1 - green 2 - cyan (bright blue) 3 - red 4 - blue-green (used for the control-panel) 5 - dark blue 6 - gold 7 - light yellow 8 to 15 - dark grey to white used for the stars 59 I have provided a sample database of several objects to demonstrate the file. The gold objects are radio sources, green ones are pulsars, quasars are cyan, and yellow is the 1987 Supernova. comet Bradfield, which was visible in the late 1987 is plotted in the blue-green. You may also add up to 12 lines of extra commentary to each object by the use of separate "comment" files. These will be displayed when you click on top of each object using the point-and-identify feature. Each of the files must be named "uoX.etxt", where the "X" is the serial number of the object. So for the above example, the comment file would be "uo2.etxt". 60 OPERATIONAL TIPS If you are running DISTANT SUNS on with 1 meg of memory or more and without a hard-disk, I would recommend purchasing FACC from ASDG Inc. and running it in conjunction with my program. FACC will greatly speed up disk access, especially when using point-and-identify. Also DISTANT SUNS uses several overlays in order to cut the size of the program in RAM. Overlaying a program is the process of loading in pieces as they are needed, then purging them from memory when done. The telescope is one example, since it will not be used all of the time. FACC will make this process virtually instantaneous. Some of you may move DISTANT SUNS over to a hard-disk. There is a slight chance that a file might be dropped in the process. If so, the program will probably bite it along the way. Should this happen, starting DISTANT SUNS from CLI might print out some internal diagnostic messages that could help identify the problem. If you get the extended-data disk and want to put it on a hard-disk, you can install it in place of the smaller star files it replaces. You may notice that the Yale disk directory structure is the same as the DISTANT SUNS disk. All you need to do is move the Yale files ":data/stars/stars.bin" and ":data/pidat/stars.txt" over to the main DISTANT SUNS directory. 61 TECHNICAL NOTES DISTANT SUNS was written in about 3 1/2 years worth of spare time from February 1986 to August 1989 using Manx Aztec-C. The system was a standard Amiga 1000 with a 2 Meg Alegra memory expansion, Ronin 68020 board and 65 meg hard-drive. Most of the equations used were derived from the book Practical Astronomy With Your Calculator, by Peter Duffett-Smith. Additional material was used from Astronomical Formulae for Calculators by Jean Meeus. By now you may have noticed that images of the Sun and Moon come in only two different sizes. The smaller size is correct for an FOV of 30 degrees while the larger size is accurate for 15 degrees. Because of the limited sizes, visual studies of events such as solar eclipses, transits, etc., are necessarily going to have limited accuracy and utility. In other words, what might appear to be an eclipse with an FOV of 75 degrees might just be caused by oversized images interfering with each other. That is why 30 degree FOV is recommended for eclipses. Furthermore, any timings derived from DISTANT SUNS will be only approximate. You may notice that when running the time at some high rate of speed, the Moon will move in a rather erratic fashion. This comes as a result of precision errors in the computation. Aztec C permits the use of either single or double precision, but not both at the same time. Since double precision is much slower than the single variety, I chose the latter. The lunar calculations require the use of very large numbers, but also require precision to several digits beyond the decimal point. When it is limited, the position of the Moon jumps in noticeably discrete steps. Also, the accuracy of planetary and stellar positions suffer the further you travel from the current date. Furthermore, I am using the Motorola Fast-Floating Point (FFP) math 62 libraries which likewise sacrifice precision for speed. I expect these problems to be corrected in the future with new compilers and libraries. But since my main concern was the authenticity of the display for current dates some of the more obscure astronomical behaviors would have to suffer until the supporting software catches up. I know that this will upset some astrophysics grad students out there, but if you want ultimate accuracy, use your department's VAX. The calendar used by DISTANT SUNS is the traditional Gregorian calender introduced by Pope Gregory XIII in 1582. The Julian calender, in use since 45 BC, had years which were slightly too long. As a result, dates had now slipped by a full 10 days from where they should have been. This error was eliminated by the weirdest October on record, when people went to bed on the 5th and woke up on the 15th. You will notice that DISTANT SUNS will not let you enter dates within this period. Also, there is no year "0", so the years go from 1 BC to 1 AD. The stellar databases used in DISTANT SUNS, for all their glory, do have problems. When developing the program, I noticed that there were some very bright starts where none should be. I traced it down to some empty magnitude entries in the original database which the program interpreted as magnitude zero. No doubt there are similar problems waiting to be found, so if you find errors in the database don't hesitate to report them so they may be corrected in future versions. I have been asked by many as to why I don't do double-buffering for the screen scrolls (showing one image while building up another elsewhere in memory). In order to do this I would need to have a second full size star window to alternate with which would take up an additional 54K of memory. On a 512K machine, there just isn't enough space, although future versions may permit it if extra memory is available. 63 They say a program is never really tested until it hits the dealers shelves. No doubt it is true in this case as in all others. I'm sure that there are bugs lurking in the recesses of some arcane structure just waiting to be released. Should you have the misfortune of discovering one of these please call Virtual Reality Laboratories, Inc. and report it. Before you do, see if it can be duplicated, and if so, carefully record all of the steps. This is essential if you should release one of the dreaded Gurus from his electronic prison. DISTANT SUNS doesn't send screen dumps directly to the printer because that requires making a snapshot in memory to avoid typing up the machine. This snapshot would require 64K or memory which just isn't available on the basic machines. Also, dumping it to an IFF file means that you can load it in to your favorite paint program and add any notes or diagrams to the image, as well as optimizing the colors for your printer. Many have asked shy I don't do stars or deep-sky objects in the telescope. With stars I would have to have a much larger database to draw from, since a simple (real) telescope would reveal literally millions of stars. The storage on disk and in memory would be far too prohibitive. With deep-sky objects, I would be required to store potentially dozens of images in chip RAM at once to be able to give the user instant access to any image within the telescope's region. Considering the fact that each image could easily take from 1K to 3K of memory, you can see that you would run out of space in short order. (Not to mention the time it would take to load them into memory). 64 APPENDIX A MESSIER CATALOGUE MESS NGC CON TYPE R.A. DECL MAG DIST(1) COMMENTS M 1 1952 Tau PlNeb O53l.5 +2159 8.2 6K Crab Nebula M 2 7089 Aqr GlbCl 2130.9 -0103 6.3 50K M 3 5272 CVn GlbCl 1339.9 +2838 6.3 30K M 4 6121 Sco GlbCl 1620.6 -2624 6.4 10K M 5 5904 Ser GlbCl 1516.0 +0216 6.2 30K M 6 6405 Sco OpCl 1736.8 -3211 5.3 2K M 7 6475 Sco OpCl 1750.7 -3448 4.1 1K M 8 6523 Sgr DfNeb 1801.6 -2420 6.0 6.5K Lagoon Nebula M 9 6333 Oph GlbCl 1716.2 -1828 7.3 25K M 10 6254 Oph GlbCl 1654.5 -0402 6.7 16K M 11 6705 Sct OpCl 1848.4 -0620 6.3 6K M 12 6218 Oph GlbCl 1644.6 -0152 6.6 16K M 13 6205 Her GlbCl 1639.9 +3633 5.7 25K M 14 6402 Oph GlbCl 1735.0 -0313 7.7 23K M 15 7078 Peg GlbCl 2127.6 +1157 6.0 40K M 16 6611 Ser OpCl 1816.0 -1348 6.4 7K nebula & cluster M 17 6618 Sgr DfNeb 1818.0 -1612 7.5 5K Omega Nebula & cluster M 18 6613 Sgr OpCl 1817.0 -1709 7.5 6K M 19 6273 Oph GlbCl 1659.5 -2611 6.6 20K M 20 6514 Sgr DfNeb 1758.9 -2302 9.0 2.2K Trifid Nebula M 21 6531 Sgr OpCl 1801.8 -2230 6.5 3K M 22 6656 Sgr GlbCl 1833.3 -2358 5.9 10K M 23 6494 Sgr OPCl 1754.0 -1901 6.9 4.5K M 24 6603 Sgr OpCl 1815.5 -1827 4.6 10K star cloud M 25 IC4725 Sgr OpCl 1828.8 -1917 6.5 2K open cloud M 26 6694 Sct OpCl 1842.5 -0927 9.3 5K M 27 6853 Vul PlNeb 1957.4 +2235 7.6 1250 Dumbbell Nebula M 28 6626 Sgr GlbCl 1821.5 -2454 7.3 15K M 29 6913 Cyg OpCl 2022.2 +3821 7.1 7.2K M 30 7099 Cap GlbCl 2137.5 -2325 8.4 40K M 31 224 And SpGal 0040.0 +4100 4.8 2,200K Andromeda Galaxy M 32 221 And ElGal 0040.0 +4036 8.7 2,200K satellite of M31 M 33 598 Tri SpGal 0131.1 +3024 6.7 2,300K Sc M 34 1039 Per OpCl 0238.8 +4234 5.5 1,400 M 35 2168 Gem OpCl 0605.7 +2420 5.3 2,800 M 36 1960 Aur OpCl 0532.0 +3407 6.3 4,100 M 37 2099 Aur OpCl 0549.0 +3233 6.2 4,600 M 38 1912 Aur OpCl 0525.3 +3548 7.4 4,200 M 39 7092 Cyg OpCl 2130.4 +4813 5.2 900 M 40 WNC4 UMa DS 1220.0 +5822 9.1 double star M 41 2287 CMa OpCl 0644.9 -2042 4.6 2,400 M 42 1976 Ori DfNeb 0532.9 -0525 4.0 1K Great Orion Nebula 65 MESS NGC CON TYPE R.A. DECL MAG DIST(1) COMMENTS M 43 1982 0ri DfNeb 0533.1 -0518 9.1 1K part of Great Orion Neb. M 44 2632 Cnc OpCl 0837.5 +1952 3.7 500 Praesepe M 45 Tau OpCl 0343.9 +2358 1.6 400 The Pleiades M 46 2437 Pup OpCl 0739.6 -1442 6.0 5,400 M 47 2422 Pup OpCl 0734.3 -1422 4.5 1,600 M 48 2548 Hya OpCl 0811.2 -0538 5.3 1,000 M 49 4472 Vir ElGal 1227.3 +0816 8.6 M 50 2323 Mon OpCl 0700.5 -0816 6.3 3K M 51 5194 CVn SpGal 1327.8 +4727 8.1 15000K Whirlpool Galaxy M 52 7654 Cas OpCl 2322.0 +6120 7.3 7K M 53 5024 Com GlbCl 1310.5 +1826 7.6 60K M 54 6715 Sgr GlbCl 1852.0 -3032 8.0 50K M 55 6809 Sgr GlbCl 1936.9 -3103 5.0 20K M 56 6779 Lyr GlbCl 1914.6 +3005 8.2 40K M 57 6720 Lyr PlNeb 1851.7 +3258 9.3 4,100 Ring Nebula M 58 4579 Vir SpGal 1235.1 +1205 9.2 70000K SBb-barred spiral galaxy M 59 4621 Vir ElGal 1239.5 +1155 9.6 70000K M 60 4649 Vir ElGal 1241.1 +1149 8.9 70000K M 61 4303 Vir SpGal 1219.4 +0445 10.1 70000K Sc-barred spiral galaxy M 62 6266 Oph GlbCl 1658.1 -3003 6.6 26K M 63 5055 CVn SpGal 1313.5 +4217 9.5 14500K Sb M 64 4826 Com SpGal 1254.3 +2157 8.8 12000K Sb M 65 3623 Leo SpGal 1116.3 +1323 9.3 35000K Sa M 66 3627 Leo SpGal 1117.6 +1317 8.2 35000K Sb M 67 2682 Cnc OpCl 0848.3 +1200 6.1 2,250 Alternate decl:0847.8 M 68 4590 Hya GlbCl 1236.8 -2629 8.0 40K M 69 6637 Sgr GlbCl 1828.1 -3223 8.9 25K M 70 6681 Sgr GlbCl 1840.0 -3221 9.6 65K M 71 6838 Sge GlbCl 1951.4 +1839 9.0 8,500 M 72 6981 Aqr GlbCl 2050.7 -1244 9.8 60K M 73 6994 Aqr OpCl 2056.4 -1250 9.0 cluster of 4 stars M 74 628 Psc SpGal 0134.0 +1532 10.2 20000K Sc M 75 6864 Sgr GlbCl 2003.2 -2204 8.0 100K M 76 650 Per PlNeb 0138.8 +5119 10.2 3,400 M 77 1068 Cet SpGal 0240.1 -0014 8.9 30000K Sb-Seyfert galaxy M 78 2068 Ori DfNeb 0544.2 +0002 10.3 1,600 emmission nebula M 79 1904 Lep GlbCl 0522.2 -2434 8.4 54K M 80 6093 Sco GlbCl 1614.1 -2252 7.7 36K M 81 3031 UMa SpGal 0951.5 +6918 7.9 7000K Sb M 82 3034 UMa IrGal 0951.9 +6956 8.8 7000K M 82 6341 Her GlbCl 1715.6 +4312 6.1 28K M 83 5236 Hya SpGal 1334.3 -2937 10.1 8000K Sc M 84 4374 Vir ElGal 1222.6 +1310 9.3 70000K M 85 4382 Com ElGal 1222.8 +1828 9.3 70000K SO M 86 4406 Vir ElGal 1223.7 +1313 9.7 70000K giant elliptical galaxy 66 MESS NGC CON TYPE R.A. DECL MAG DIST(1) COMMENTS M 87 4486 Vir ElGal 1228.3 +1240 9.2 70000K giant elliptical galaxy M 88 4501 Com SpGal 1229.5 +1442 10.2 40000K Sb M 89 4552 Vir ElGal 1233.1 +1250 9.5 70000K M 90 4569 Vir SpGal 1234.3 +1326 10.0 70000K Sb M 91 4548 Com SpGal 1232.9 +1446 9.5 40000K barred spiral galaxy M 93 2447 Pup OpCl 0742.4 -2345 6.0 36K M 94 4736 CVn SpGal 1248.6 +4123 7.9 14500K Sb M 95 3351 Leo SpGal 1041.3 +1158 10.4 25000K barred spiral galaxy M 96 3368 Leo SpGal 1044.2 +1205 9.1 25000K Sa M 97 3587 UMa PlNeb 1112.0 +5518 12.0 2,600 Owl Nebula M 98 4192 Com SpGal 1211.3 +1511 11.7 70000K Sb M 99 4254 Com SpGal 1216.3 +1442 10.7 70000K Sc M 100 4321 Com SpGal 1220.4 +1606 10.6 70000K Sc M 101 5457 UMa SpGal 1401.4 +5435 9.6 15000K Sc-same as M102 M 102 5457 UMa SpGal 1401.4 +5435 9.6 15000K Sc-same as M101 M 103 581 Cas OpCl 0129.9 +6027 7.4 8K M 104 4594 Vir SpGal 1237.3 -1121 8.7 5000K Sombrero Galaxy M 105 3379 Leo ElGal 1045.2 +1251 9.2 25000K M 106 4258 CVn SpGal 1216.5 +4735 8.6 25000K Sb M 107 6171 Oph GlbCl 1629.7 -1257 9.2 10K M 108 3556 UMa SpGal 1108.7 +5557 10.7 25000K Sb M 109 3992 UMa SpGal 1155.0 +5339 10.8 25000K barred spiral galaxy M 110 205 And ElGal 0037.6 +4125 9.4 2200K satellite of M31 67 APPENDIX B SUPPLIED NGC CATALOG NGC CON CONST R.A. DECL MAGv REMARKS 40 Cas PlNeb 0010.2 +7215 10.2 central star mag:11.4 55 Scl SpGal 0012.5 -3930 104 Tuc GlbCl 0021.9 -7221 4.5 129 Cas OpCl 0027.6 +5957 10.0 number:50 133 Cas OpCl 0028.4 +6304 9.1 number:50 134 Scl SpGal 0027.9 -3332 157 Cet SpGal 0032.3 -0840 11.2 185 Cas ElGal 0036.1 +4804 11.7 188 Cep OpCl 0039.4 +8503 9.3 number:70 205 And ElGal 0037.6 +4125 9.4 225 Cas OpCl 0040.5 +6131 9.1 number:20 246 Cet PlNeb 0044.6 -1209 8.5 central star mag:11.3 247 Cet SpGal 0044.6 -2101 253 Scl SpGal 0045.1 -2534 8.9 278 Cas ElGal 0049.2 +4718 11.3 281 Cas DfNeb 0050.4 +5919 8.6 spectrum:O5e 288 Scl GlbCl 0050.2 -2652 300 Scl SpGal 0052.6 -3758 404 And ElGal 0106.6 +3527 10.7 457 Cas OpCl 0115.9 +5804 7.5 number:100 488 Psc SpGal 0119.1 +0500 11.1 57A Psc ElGal 0122.1 +0916 11.1 584 Cet ElGal 0128.8 -0707 10.8 596 Cet ElGal 0130.3 -0717 11.5 613 Scl SpGal 0132.0 -2940 10.2 659 Cas OpCl 0140.8 +6028 9.8 number:30 663 Cas OpCl 0142.6 +6101 7.1 number:80 720 Cet ElGal 0150.6 +1359 10.5 752 And OpCl 0154.7 +3725 7.0 number:70 772 Ari SpGal 0156.6 +1846 10.9 779 Cet SpGal 0157.2 -0612 11.3 821 Ari ElGal 0205.6 +1046 11.2 869 Per OpCl 0215.5 +5655 4.4 number:35O-half dbl clus 884 Per OpCl 0218.9 +5653 4.7 number:300-half dbl clus 925 Tri SpGal 0224.3 +3322 936 Cet SpGal 0225.1 -0122 10.7 1022 Cet SpGal 0236.1 -0653 11.2 1023 Per ElGal 0237.2 +3852 1052 Cet ElGal 0238.6 -0828 11.2 1084 Eri SpGal 0243.5 -0747 11.0 1097 For SpGal 0244.3 -3029 68 NGC CON CONST R.A. DECL MAGv REMARKS 1232 Eri SpGal 0307.5 -2046 1245 Per OpCl 0311.2 +4703 6.9 number:40 1261 Hor GlbCl 0310.9 -5525 1316 For SpGal 0320.7 -3725 1332 Eri ElGal 0324.1 -2131 10.4 1342 Per OpCl 0328.4 +3709 7.1 number:40 1365 For SpGal 0331.8 -3618 1395 Eri ElGal 0336.3 -2311 1398 For SpGal 0336.8 -2630 1399 For ElGal 0336.6 -3537 1407 Eri ElGal 0337.9 -1844 10.6 1499 Per DfNeb 0400.1 +3617 4.1 California 1501 Cam PlNeb 0402.6 +6047 13.3 central star mag:13.4 1502 Cam OpCl 0403.0 +6211 5.3 number:15 1514 Tau PlNeb 0406.1 +3038 10.8 central star mag:9.7 1528 Per OpCl 0411.4 +5107 6.2 number:80 1532 Eri SpGal 0410.2 -3300 edge-on barred spiral 1535 Eri PlNeb 0412.1 -1252 9.3 central star mag:11.8 1545 Per OpCl 0417.1 +5008 8.0 number:25 1554 Tau DfNeb 0419.9 +1925 spectrum:Gpe/Hind' s Var. 1647 Tau OpCl 0443.2 +1859 6.3 number:30 1664 Aur OpCl 0447.4 +4337 7.5 number:40 1700 Eri ElGal 0454.4 -0456 11.9 1746 Tau OpCl 0500.6 +2344 6.0 number:60 1792 Col SpGal 0503.5 -3804 1817 Tau OpCl 0509.2 +1638 7.9 number:10 1851 Col GlbCl 0512.4 -4005 8.1 1857 Aur OpCl 0516.6 +3918 8.6 number:45 1893 Aur OpCl 0522.4 +3321 8.0 number:20 1907 Aur OpCl 0524.7 +3517 9.9 number:40 1977 Ori DfNeb 0533.0 -0454 4.6 1990 Ori DfNeb 0533.7 -0114 1.8 spectrum:BOe 2023 Ori DfNeb 0539.2 -0215 7.9 spectrum:B2 2024 Ori DfNeb 0539.4 -0152 1.9 spectrum:BOne 2064 Ori DfNeb 0543.8 -0002 9.9 2112 Ori OpCl 0551.3 +0023 8.6 number:90 2141 Ori OpCl 0600.3 +1026 10.8 number:100 2158 Gem OpCl 0604.3 +2406 12.5 number:40 2169 Ori OpCl 0605.7 +1358 6.4 number:18 2174 Ori DfNeb 0606.7 +2031 7.4 spectrum :O6e 2175 Ori OpCl 0606.8 +2020 6.7 number:15 2194 Ori OpCl 0611.0 +1250 9.2 number:100 2215 Mon OpCl 0618.4 -0716 8.6 number:20 2237 Mon DfNeb 0629.6 +0440 Rosetta 2244 Mon OpCl 0629.7 +0454 6.2 number:16 69 NGC CON CONST R.A. DECL MAGv REMARKS 2261 Mon DfNeb 0636.4 +0846 8.0 spectrum:Bp/ Hubble's Var 2264 Mon OpCl 0638.4 +0956 4.7 number:20 2264 Mon DfNeb 0638.2 +0957 4.7 spectrum:07n-Cone Nebula 2266 Gem OpCl 0640.5 +2702 9.8 number:30 2281 Aur OpCl 0645.8 +4107 6.7 number:30 2286 Mon OpCl 0645.1 -0307 8.0 number:50 2298 Pup GlbCl 0647.2 -3557 10.5 2301 Mon OpCl 0649.2 +0031 5.8 number:60 2324 Mon OpCl 0700.4 +0108 8.8 number:30 2335 Mon OpCl 0704.2 -1000 9.1 number:35 2353 Mon OpCl 0712.3 -1012 5.3 number:25 2354 CMa OpCl 0712.2 -2538 8.9 number:60 2360 CMa OpCl 0715.4 -1533 9.5 number:50 2371 Gem PlNeb 0722.4 +2935 13.0 central star mag:13.3 2392 Gem PlNeb 0726.2 +2101 8.3 central star mag:10.5-Eskimo 2395 Gem OpCl 0724.3 +1341 9.4 2403 Cam SpGal 0732.0 +6543 8.9 2419 Lyn GibCl 0734.8 +3900 11.5 2420 Gem OpCl 0735.4 +2124 10.2 number:20 2421 Pup OpCl 0734.1 -2030 9.4 number:50 2422 Pup OpCl 0734.3 -1422 4.5 number:50 2423 Pup OpCl 0734.8 -1345 6.9 number:60 2438 Pup PlNeb 0739.6 -1436 11.3 central star mag:16.8 2439 Pup OpCl 0738.9 -3132 7.1 number:50 2451 Pup OpCl 0743.6 -3751 3.6 number:50 2477 Pup OpCl 0750.5 -3825 5.7 number:300 2482 Pup OpCl 0752.8 -2410 8.7 number:50 2489 Pup OpCl 0756.2 -2956 9.4 number:30 2506 Mon OpCl 0757.7 -1029 11.5 number:50 2509 Pup OpCl 0758.5 -1856 9.3 number:40 2516 Car OpCl 0759.7 -6044 3.0 number:80 2539 Pup OpCl 0808.4 -1241 8.2 number:150 2547 Vel OpCl 0808.9 -4907 5.1 number:50 2548 Hya OpCl 0811.2 -0538 5.3 number:80 2567 Pup OpCl 0816.6 -3029 8.3 number:50 2571 Pup OpCl 0816.9 -2935 7.5 number:25 2587 Pup OpCl 0821.3 -2920 9.1 number:30 2610 Hya PlNeb 0831.2 -1558 13.6 central star mag:15.7 2627 Pyx OpCl 0835.2 -2946 8.3 number:40 2655 Cam SpGal 0849.4 +7825 10.7 2658 Pyx OpCl 0841.4 -3229 9.2 number:30 2681 Lyn SpGal 0850.0 +5131 10.4 2683 Lyn SpGal 0849.6 +3338 9.6 2742 UMa SpGal 0903.7 +6041 11.2 2768 UMa ElGal 0907.8 +6016 10.5 70 NGC CON CONST R.A. DECL MAGv REMARKS 2775 Cnc SpGal 0907.7 +0715 10.7 2787 UMa SpGal 0914.9 +6925 10.9 2841 UMa SpGal 0918.6 +5112 9.3 2859 LMi SpGal 0921.3 +3344 10.7 2903 Leo SpGal 0929.3 +2144 9.1 2950 UMa SpGal 0939.1 +5905 10.9 2964 Leo SpGal 0940.0 +3205 11.0 2976 UMa SpGal 0943.2 +6808 11.4 2985 UMa SpGal 0946.0 +7231 10.6 2997 Ant SpGal 0943.5 -3059 3003 LMi SpGal 0945.6 +3339 12.7 edge-on 3021 LMi SpGal 0948.0 +3347 11.7 3077 UMa ElGal 0959.4 +6858 10.9 3079 UMa SpGal 0958.6 +5557 11.2 3115 Sex ElGal 1002.8 -0728 9.3 Spindle Nebula 3132 Vel PlNeb 1004.9 -4011 8.2 central star mag:10.6 3147 Dra SpGal 1012.8 +7339 10.9 3184 UMa SpGal 1015.2 +4140 12.1 3201 Vel GlbCl 1015.5 -4609 3242 Hya PlNeb 1022.4 -1823 9.0 central star mag:11.4-Eye Neb. 3310 UMa IrGal 1035.7 +5346 10.1 3344 LMi SpGal 1040.7 +2511 10.4 3372 Car DfNeb 1043.1 -5925 5.0 spectrum:Pec-Keyhole Neb 3377 Leo ElGal 1045.1 +1415 10.5 3384 Leo ElGal 1045.7 +1254 10.2 3412 Leo ElGal 1048.3 +1341 10.4 3486 LMi SpGal 1057.8 +2915 11.2 3504 LMi SpGal 1100.5 +2815 10.9 3511 Crt SpGal 1100.8 +2250 3521 Leo SpGal 1103.2 +0014 9.5 3585 Hya ElGal 1110.9 -2629 3607 Leo ElGal 1114.3 +1820 9.6 3621 Hya SpGal 1115.9 -3232 3626 Leo SpGal 1117.5 +1838 10.5 3628 Leo SpGal 1117.7 +1353 10.9 edge on 3631 UMa SpGal 1118.3 +5328 11.2 3646 Leo SpGal 1119.2 +2027 3675 UMa SpGal 1123.5 +4352 10.6 3810 Leo SpGal 1138.4 +1145 10.8 3877 UMa SpGal 1143.5 +4746 10.9 3893 UMa SpGal 1146.1 +4900 11.3 3923 Hya ElGal 1148.5 -2833 3941 UMa SpGal 1150.3 +3716 9.8 3945 UMa SpGal 1150.6 +6057 10.8 3949 UMa SpGal 1151.1 +4808 11.0 71 NGC CON CONST R.A. DECL MAGv REMARKS 3953 UMa SpGal 1151.2 +5237 10.7 3962 Crt ElGal 1152.2 -1342 11.3 4026 UMa ElGal 1156.9 +5114 10.7 4030 Vir SpGal 1157.8 -0049 11.0 4036 UMa ElGal 1158.9 +6210 10.7 4038 Crv SpGal 1159.3 -1835 4041 UMa SpGal 1159.7 +6225 11.0 4051 UMa SpGal 1200.6 +4448 11.0 4088 UMa SpGal 1203.0 +5049 10.9 4105 Hya ElGal 1204.1 -2930 4111 UMa ElGal 1204.5 +4321 9.7 4125 Dra ElGal 1205.7 +6527 10.2 4143 CVn ElGal 1207.1 +4249 11.0 4214 CVn SpGal 1213.0 +3636 10.3 4216 Vir SpGal 1213.4 +1325 10.4 4244 CVn SpGal 1215.0 +3805 11.9 4251 Com SpGal 1215.7 +2827 10.2 4261 Vir ElGal 1216.8 +0606 10.3 4274 Com SpGal 1217.4 +2953 10.8 4278 Com ElGal 1217.7 +2934 10.3 4314 Com SpGal 1220.0 +3010 10.8 4361 Crv PlNeb 1221.9 -1829 10.8 central star mag:l2.8 4365 Vir ElGal 1222.0 +0736 11.1 4395 CVn SpGal 1223.4 +3349 4414 Com SpGal 1224.0 +3130 9.7 4429 Vir SpGal 1224.9 +1123 11.2 4438 Vir SpGal 1225.3 +1317 10.8 4449 CVn IrGal 1225.8 +4422 9.2 4450 Com SpGal 1225.9 +1721 10.0 4459 Com ElGal 1226.5 +1514 10.9 4465 Vir ElGal 1225.2 +1321 10.3 4473 Com ElGal 1227.3 +1342 10.1 4477 Vir SpGal 1227.6 +1355 10.7 4990 CVn SpGal 1228.3 +4155 9.7 4494 Com ElGal 1228.9 +2603 9.6 4526 Vir ElGal 1231.6 +0758 10.9 4535 Vir SpGal 1231.8 +0828 4536 Vir SpGal 1231.9 +0228 11.9 4546 Vir ElGal 1232.9 -0331 10.0 4565 Com SpGal 1233.9 +2616 10.2 edge-on 4631 CVn SpGal 1238.8 +3249 9.3 edge-on 4636 Vir ElGal 1240.3 +0257 10.4 4643 Vir SpGal 1240.8 +0215 10.6 4656 CVn SpGal 1241.6 +3226 11.2 4660 Vir ElGal 1242.0 +1126 10.9 72 NGC CON CONST R.A. DECL MAGv REMARKS 4666 Vir SpGal 1242.6 -0012 11.4 4697 Vir ElGal 1246.0 -0532 9.6 4699 Vir SpGal 1246.5 -0824 9.3 4725 Com SpGal 12A8.1 +2546 8.9 4753 Vir SpGal 1249.8 -0055 10.8 4754 Vir ElGal 1249.7 +1135 10.5 4762 Vir SpGal 1250.4 +1131 11.0 4775 Vir SpGal 1251.1 -0621 4781 Vir SpGal 1251.8 -1016 11.2 4800 CVn SpGal 1252.4 +4648 11.1 4826 Vir SpGal 1254.3 +2157 8.8 4856 Vir ElGal 1256.7 -1446 4900 Vir SpGal 1258.2 +0246 11.3 4945 Cen SpGal 1302.4 -4901 4958 Vir ElGal 1303.1 -0745 10.9 4995 Vir SpGal 1307.0 -0734 11.2 5005 CVn SpGal 1308.5 +3719 9.8 5033 CVn SpGal 1311.2 +3651 10.3 5044 Vir ElGal 1312.8 -1608 11.2 5053 Com GlbCl 1313.9 +1757 5068 Vir SpGal 1316.2 -2047 5102 Cen ElGal 1319.1 -3623 5128 Cen IrGal 1322.4 -4245 7.2 Centaurus-A 5139 Cen GlbCl 1323.8 -4703 3.7 Omega Centauri 5195 CVn IrGal 1327.9 +4731 8.4 Pre-companion to M51 5248 Boo SpGal 1335.1 +0908 11.3 5322 UMa ElGal 1347.6 +6026 10.0 5363 Vir ElGal 1353.6 +0529 10.7 5377 CVn SpGal 1354.3 +4727 11.2 5427 Vir SpGal 1400.8 -0547 5466 Boo GlbCl 1403.2 +2846 8.5 5566 Vir SpGal 1417.8 +0411 10.4 5746 Vir SpGal 1442.3 +0210 10.1 5775 Vir SpGal 1451.5 +0345 5824 Lup GlbCl 1500.9 -3253 10.1 I 5846 Vir ElGal 1504.0 +0148 10.5 EO 5873 Lup PlNeb 1509.4 -3754 9.7 5897 Lib GlbCl 1514.5 -2050 10.9 5982 Dra ElGal 1537.6 +5932 10.9 5986 Lup GlbCl 1542.8 -3737 8.7 6058 Her PlNeb 1602.8 +4049 12.3 central star mag:13.4 6139 Sco GlbCl 1524.3 -3844 6144 Sco GlbCl 1624.2 -2556 6210 Oph PlNeb 1642.5 +2353 9.7 central star mag:12.5 6268 Sco OpCl 1658.6 -3939 9.5 number:30 73 NGC CON CONST R.A. DECL MAGv REMARKS 6281 Sco OpCl 1701.4 -3749 8.6 number:25 6284 Oph GlbCl 1701.5 -2441 9.7 6293 Oph GlbCl 1707.1 -2630 8.4 6304 Oph GlbCl 1711.4 -2924 9.8 6316 Oph GlbCl 1713.4 -2805 6352 Ara GlbCl 1721.6 -4826 6356 Oph GlbCl 1720.7 -1746 8.7 6369 Oph PlNeb 1726.3 -2344 9.9 central star mag:16.6 6383 Sco OpCl 1731.4 -3233 5.5 number:12 6388 Sco GlbCl 1732.6 -4443 6397 Ara GlbCl 1736.8 -5339 6400 Sco OpCl 1736.1 -3655 8.9 number:25 6441 Sco GlbCl 1746.8 -3702 6445 Sgr PlNeb 1746.3 -2000 13.2 central star mag:19.1 6503 Dra SpGal 1549.9 +7010 9.6 6528 Sgr GlbCl 1801.6 -3004 6541 CrA GlbCl 1804.4 -4344 6543 Dra PlNeb 1758.8 +6638 8.8 central star mag:11.1 6572 Oph PlNeb 1809.7 +0650 9.6 central star mag:12.0 6584 Tel GlbCl 1814.6 -5214 6620 Sgr PlNeb 1818.7 -2652 15.0 central star mag:15.8 6624 Sgr GlbCl 1820.5 -3023 6629 Sgr PlNeb 1822.7 -2314 10.6 central star mag:13.6 6638 Sgr GlbCl 1827.9 -2532 9.8 6652 Sgr GlbCl 1832.5 -3302 6664 Sct OpCl 1734.0 -0816 8.9 number:25 6709 Aql OpCl 1749.1 +1017 8.1 number:40 6712 Sd GlbCl 1850.3 -0847 8.9 6723 Sgr GlbCl 1856.2 -3642 6755 Aql OpCl 1905.3 +0409 8.3 number:50 6760 Aql GlbCl 1908.6 +0057 10.7 6790 Aql PlNeb 1920.4 +0124 11.4 central star mag:18.4 6803 Aql PlNeb 1928.9 +0958 11.4 central star mag:14.1 6811 Cyg OpCl 1936.7 +4627 9.2 number:50 6818 Sgr PlNeb 1941.1 -1417 9.9 central star mag:15.0 6819 Cyg OpCl 1939.6 +4006 10.1 number:150 6822 Sgr IrGal 1942.1 -1453 10.0 6826 Cyg PlNeb 1943.4 +5024 8.8 central star mag:10.8 6830 Vul OpCl 1948.9 +2258 9.0 number:20 6842 Vul PlNeb 1953.0 +2909 13.6 central star mag:14.1 6871 Cyg OpCl 2004.0 +3538 5.6 number:60 6879 Sge PlNeb 2008.1 +1646 12.1 central star mag:15.2 6885 Vul OpCl 2009.9 +2620 9.1 number:35 6886 Sge PlNeb 2010.5 +1950 12.2 central star mag:16.6 6891 Aql PlNeb 2012.8 +1235 11.4 central star mag:11.6 74 NGC CON CONST R.A. DECL MAGv REMARKS 6894 Cyg PlNeb 2014.4 +3025 14.4 central star mag:17.0 6905 Del PlNeb 2020.2 +1957 11.9 central star mag:14.2 6910 Cyg OpCl 2021.3 +4037 6.7 number:40 6934 Del GibCl 2031.7 +0714 9.2 6939 Cep OpCl 2030.4 +6028 10.0 number:80 6940 Vul OpCl 2032.5 +2808 8.2 number:100 6946 Cep SpGal 2033.9 +5958 6960 Cyg DfNeb 2043.6 +3032 8.0 Cirrus, Veil Nebula 7000 Cyg DfNeb 2057.0 +4408 1.3 spectrum:cA2e/ No America 7006 Del GlbCl 2059.1 +1600 10.3 7009 Aqr PlNeb 2101.4 -1134 8.4 central star mag:l2-Saturn Neb. 7023 Cep DfNeb 2101.4 +6758 7.2 spectrum:B5e 7026 Cyg PlNeb 2104.6 +4739 12.7 central star mag:14.8 7027 Cyg PlNeb 2105.1 +4202 10.4 central star mag:17.1 7086 Cyg OpCl 2129.8 +5122 9.4 number:50 7128 Cyg OpCl 2142.4 +5329 11.2 number:20 7209 Lac OpCl 2201.8 +4616 7.6 number:50 7217 Peg SpGal 2205.6 +3107 7243 Lac OpCl 2213.2 +4938 7.4 number:40 7293 Aqr PlNeb 2227.0 -2106 6.5 central star mag:l3-Helix Neb. 7331 Peg SpGal 2234.7 +3410 9.7 7448 Peg SpGal 2257.6 +1543 11.2 7541 Psc SpGal 2312.2 +0415 12.1 7635 Cas PlNeb 2318.5 +6054 8.5 central star mag:8.5 7662 And PlNeb 2323.5 +4214 8.9 central star mag:12.5 7723 Aqr SpGal 2336.4 -1314 11.1 7727 Aqr SpGal 2337.3 -1234 10.7 7789 Cas OpCl 2254.5 +5626 9.6 number:200 7790 Cas OpCl 2254.5 +6056 7.1 number:25 7793 Scl SpGal 2355.3 -3251 9.7 OpCl = Open Cluster GlbCl = Globular Cluster PlNeb = Planetary Nebula DfNeb = Diffuse Nebula SpGal = Spiral Galaxy ElGal = Elliptical Galaxy IrGal = Irregular Galaxy 75 APPENDIX C PLANETARY DATA Mean distance Period of Period of from Sun revolution Inclination Diameter rotation on in millions around the to ecliptic (miles) axis of miles Sun Mercury 36.0 87d.9 7 0 3,100 58.66d Venus 67.2 224d.7 3 24 7,700 243.2d Earth 93.0 365d.2 0 0 7,927 23h56m Mars 141.7 1y.8 1 51 4,200 24h37m Jupiter 483.8 11y.8 1 18 88,700 9h50m Saturn 887.1 29y.4 2 29 75,100 16h39m Uranus 1783.9 84y.0 0 46 32,000 12.8h Neptune 2795.4 164y.7 1 46 27,700 15.8h Pluto 3675.2 248y.4 17 9 1,500(?) 6d8h(?) Inclination Surface Number Mean Max. pf equator gravity Density of velocity Stellar to orbit earth = 1 H O-1 Satellites in orbit mag. plane 2 (m/sec) Mercuy 7 0.28 3.8 0 30 -1.2 Venus - 0.85 5.1 0 22 -4.4 Earth 23.4 1.00 5.5 1 18.5 -- Mars 25.2 0.38 4.0 2 15 -2.8 Jupiter 3. 1 2.6 1.3 16 8 -2.5 Saturn 26.8 1.2 0.7 17 6 -0.4 Uranus 98 1.1 1.3 15 4 +5.7 Neptune 29 1.4 2.2 2 3 +7.8 Pluto -- -- >1.0 1 <3 +14 76 APPENDIX D MAJOR VISUAL METEOR SHOWS Single Normal Position at Observer Duration to Max hourly 1/4 Strength Shower Date R.A. De Rate of Max. h m days Quadrantids Jan. 4 15 28 +50 40 1.1 Lyrids Apr. 22 18 16 +34 15 2.3 ii Aquarids May 5 22 22 -1 20 3 S.@ Aquarids July 29 22 36 -17 20 7 Perseids Aug. 12 03 04 +58 50 4.5 Orionids Oct. 21 06 20 +15 25 2 S. Taurids Nov. 3 03 32 +14 15 -- Leonids Nov. 18 10 08 +22 15 -- Geminids Dec. 14 07 32 +32 50 2.5 Ursids Dec. 23 14 28 +7 8 15 2.2 *Peak dates may vary +/- 1 day from year to year. Call your Local planetarium or University Astronomical Dept. for more timely information. 77 APPENDIX E LOCATION/TIME ZONES OF MAJOR CITIES Name Latitude Longitude State, Country Time Zone Deg Min NS Deg Min EW Accra 5 33 N 0 15 W Ghana, Africa 0 Albuquerque 35 05 N 106 38 W New Mexico, USA +7 Anchorage 61 10 N 149 53 W Alaska, USA +10 Amsterdam 52 21 N 4 54 E Netherlands, Europe -1 Ankara 39 55 N 32 50 E Turkey, Asia Minor -2 Asuncion 25 15 S 57 40 W Paraguay, S. Am. +4 Athens 38 00 N 23 44 E Greece, Europe -2 Atlanta 33 45 N 84 23 W Georgia, USA +5 Baghdad 33 20 N 44 26 E Iraq, Middle East -3 Baltimore 39 17 N 76 37 W Maryland, USA +5 Bangkok 13 44 N 100 30 E Thailand, Asia -7 Beirut 33 52 N 35 30 E Lebanon, Middle East -2 Benghazi 32 07 N 20 05 E Libya, Africa -2 Berlin 52 32 N 13 25 E W. Germany, Europe -1 Bern 46 57 N 7 26 E Switzerland, Europe -1 Bombay 18 56 N 72 51 E India, Asia -5.5 Bonn 50 44 N 7 06 E W. Germany, Europe -1 Boston 42 20 N 71 05 W Massachusetts, USA +5 Brussels 50 50 N 4 21 E Belgium, Europe -1 78 Name Latitude Longitude State, Country Time Zone Deg Min NS Deg Min EW Bucharest 44 25 N 26 07 E Romania, Europe -2 Buenos Aires 34 40 S 56 30 W Argentina, S. Am. +3 Cairo 30 03 N 31 15 E Egypt, Africa -2 Calgary 51 03 N 114 05 W Alberta, Canada +7 Cape Town 33 56 S 18 28 E South Africa, Africa -2 Caracas 10 35 N 66 56 W Venezuela, S. Am. +4.5 Casablanca 33 39 N 7 35 W Morocco, Africa 0 Chicago 41 59 N 87 38 W Illinois, USA +6 Cincinnati 39 06 N 84 31 W Ohio, USA +5 Cleveland 41 30 N 81 41 W Ohio, USA +5 Dakar 14 38 N 17 27 W Senegal, Africa 0 Dallas 32 47 N 96 48 W Texas, USA +6 Denver 39 45 N 105 00 W Colorado, USA +7 Des Moines 45 35 N 93 35 W Iowa, USA +6 Detroit 42 20 N 83 03 W Michigan, USA +5 Dublin 53 20 N 6 15 W Ireland, Europe 0 El Paso 31 45 N 106 29 W Texas, USA +7 Fairbanks 64 51 N 147 43 W Alaska, USA +10 Hanoi 21 01 N 105 52 E Vietnam, Asia -8 Havana 23 07 N 82 25 W Cuba, Caribbean +5 Helsinki 60 08 N 25 00 E Finland, Europe -2 Hiroshima 34 23 N 132 27 E Japan, Asia -9 79 Name Latitude Longitude State, Country Time Zone Deg Min NS Deg Min EW Hong Kong 22 15 N 114 11 E Asia -8 Honolulu 21 19 N 157 52 W Hawaii, USA +10 Houston 29 46 N 95 22 W Texas, USA +6 Indianapolis 39 46 N 86 09 W Indiana, USA +5 Istanbul 41 02 N 28 57 E Turkey, Asia Minor -3 Jerusalem 31 47 N 35 13 E Israel, Middle East -2 Johnannesburg 26 10 N 28 02 E South Africa, Africa -2 Kabul 34 30 N 69 10 E Afghanistan, Asia -5 Kansas City 39 05 N 94 37 W Kansas/Missouri, USA +6 Karachi 24 51 N 67 02 E Pakistan, Asia -5 Kiev 50 26 N 30 31 E USSR, Europe -3 Kyoto 35 02 N 135 45 E Japan, Asia -9 Lagos 6 27 N 3 28 E Nigeria, Africa -1 Las Vegas 36 11 N 115 08 W Nevada, USA +8 Leningrad 59 55 N 30 25 E USSR, Europe -3 Lima 12 06 S 77 03 W Peru, S. America +5 Lisbon 38 44 N 9 08 W Portugal, Europe 0 London 51 30 N 0 10 W England, Europe 0 Los Angeles 34 00 N 118 15 W California, USA +8 Madrid 40 25 N 3 43 W Spain, Europe -1 Manila 14 37 N 120 58 E Phillipines -8 Marrakech 31 49 N 8 00 W Morocco, Africa 0 80 Name Latitude Longitude State, Country Time Zone Deg Min NS Deg Min EW Mecca 21 26 N 39 49 E Saudi Arabia, M. East -3 Melbourne 37 45 S 144 58 E Victoria, Australia -10 Mexico City 19 25 N 99 10 W Mexico +6 Miami 26 45 N 80 15 W Florida, USA +5 Milwaukee 43 02 N 87 55 W Wisconsin, USA +6 Minneapolis 45 00 N 93 15 W Minnesota, USA +6 Montreal 45 31 N 73 34 W Quebec, Canada +5 Moscow 55 45 N 37 42 E USSR, Europe -3 Nairobi 1 17 S 36 50 E Kenya, Africa -3 Mew Delhi 28 37 N 77 13 E India, Asia -5.5 New Orleans 30 00 N 90 03 W Louisiana, USA +6 New York 40 43 N 74 01 W New York, USA +5 Oklahoma City 35 28 N 97 32 W Oklahoma, USA +6 Omaha 41 15 N 96 00 W Nebraska, USA +6 Oslo 59 56 N 10 45 E Norway, Europe -1 Paris 48 52 N 2 20 E France, Europe -1 Perth 31 58 S 115 49 E West Australia -8 Philadelphia 40 00 N 75 10 W Pennsylvania, USA +5 Phoenix 33 30 N 112 03 W Arizona, USA +7 Pittsburgh 40 26 N 80 00 W Pennsylvania, USA +5 Prague 50 06 N 14 26 E Czechoslovakia, Europe -1 Quebec 46 50 N 71 15 W Quebec, Canada +5 81 Name Latitude Longitude State, Country Time Zone Deg Min NS Deg Min EW Rangoon 16 46 N 96 10 E Burma, Asia -6.5 Reykjavik 64 09 N 21 58 W Iceland +1 Rio de Janerio 22 53 S 43 17 W Brazil, S. America +3 Rome 41 53 N 12 30 E Italy, Europe -1 Saigon 10 46 N 106 43 E Vietnam, Asia -7 Salt Lake City 40 45 N 111 55 W Utah, USA +7 San Francisco 37 45 N 122 27 W California, USA +8 San Juan 18 29 N 66 08 W Puerto Rico, USA +4 Santiago 33 30 S 70 40 W Chile, S. America +4 Seattle 47 36 N 122 20 W Washington, USA +5 Seoul 37 30 N 127 00 E Korea, Asia -9 Singapore 1 17 N 105 51 E Malacca, Asia -7.5 Stockholm 59 20 N 18 05 E Sweden, Europe -1 Sydney 33 55 S 151 10 E New S. Wales, Aus. -10 Taipei 25 05 N 121 32 E Taiwan, Asia -8 Tananarive 18 52 S 47 30 E Madagascar -3 Teheran 35 40 N 51 26 E Iran, Middle East -3.5 Thule 77 30 N 69 29 W Greenland +4 Timbuktu 16 49 N 2 59 E Mali, Africa 0 Tokyo 35 40 N 139 45 E Japan, Asia -9 Toronto 43 39 N 79 23 W Ontario, Canada +5 Tripoli 32 58 N 13 12 E Libya, Africa -2 82 Name Latitude Longitude State, Country Time Zone Deg Min NS Deg Min EW Tunis 36 50 N 10 13 E Tunisia, Africa -1 Vancouver 49 13 N 123 06 W Br. Columbia, Canada +5 Vienna 48 13 N 16 20 E Austria, Europe -1 Vladivostok 43 09 N 131 53 E USSR, Asia -10 Warsaw 52 15 N 21 00 E Poland, Europe -1 Washington, DC 38 55 N 77 00 W USA +5 Wellington 41 17 S 174 47 E New Zealand -12 Winnipeg 49 53 N 97 10 W Manitoba, Canada +6 Zanzibar 6 10 S 39 11 E Tanzania, Africa -3 83 APPENDIX F SUPPLEMENTARY READING "Scientific Reports on Viking Missions (Mars)", Science, Vol. 193, No. 4255, August 1976, pp. 75-815; Vol. 194, No, 4260, October 1976, pp. 57-110; Vol. 194, No. 4271, December 1976, pp. 1274-1353. "Scientific Reports on Voyager Missions (Jupiter)", Science, Vol. 204, No. 4396, June 1979, pp. 945-1008; Vol, 206, No. 4421, pp. 925-996. Abell, George O., Exploration of the Universe, New York, Holt Rienhart and Winston, 3rd Ed. 1975. Anon., The Earth and Man, New York, Rand McNally & Company, 1972. Anon., Space Exploration (Merit Badge Library #13354), Boy Scouts of America, Scout Equipment Center 289 Park Avenue South, New York City. Ashbrook, Joseph, "Astronomical Scrapbook: Some Bunchings of Pianets", Sky and Telescope, November 1973, pp. 300 & 305. Asimov, Issac, Asimov on Astronomy, New York, Doubleday, 1975. Asimov, Issac, Exploring the Earth and the Cosmos, New York, Crown Publishers, 1982. Beatty, J. Kelly, Brian O'Leary, Andrew Chaikin (Ed), The New Solar System, 2nd Ed., Cambridge, Massachusetts, Cambridge Univ. Press. 84 Bergamini, David et al, The Universe, New York/Chicago, Time Inc., 1962. (Life Nature Library) Breed, Joseph B. III, Stars for the Space Age, New York, World Publishing/Times Mirror, 1971. Clarke, Arthur C., The Exploration of Space, Revised Ed., 1979. Duffet-Smith, Peter, Practical Astronomy With Your Calculator, Cambridge Univ. Press, 1981. Ernst, Br., TJ. E. De Vries, Atlas of the Universe, London/New York, Thomas Nelson and Sons Ltd., 1961. Friedman, H., The Amazing Universe, Washington D.C., National Geographic Society, 1975. Gardner, Martin, The Relativity Explosion: A Lucid Account of Why Quasars, Pulsars, Black Holes & the New Atomic Clocks Are Vindicating Einstein's Revolutionary Theory, Random, 1976. Hirschfeld, Alan, Roger Sinnott (Ed.) Catalogue 2000.0, Vol. 1: Stars to Magnitude 8.0, Cambridge, Mass., Cambridge Univ. Press, 1982. Hughes David, The Star of Bethlehem: An Astronomer's Confirmation, Walker & Co., 1979. Krupp, E.C., Echoes of the Ancient Skies, New York, Harper & Row, 1983. Neugebauer, Otto, A History of Ancient Mathematical Astronomy, Berlin, Springer, 1975. 85 Neugebauer, Otto, H.B. Van Hoesen, "Greek Horoscopes", Memoirs of the American Philosophical Society, Vol. 48, Philadelphia, 1959. Newton, Robert R., Ancient Astronomical Observations & the Accelerations of the Earth & Moon, Baltimore/London, Johns Hopkins Press, 1970 Norville, Warren, Celestial Navigations Step by Step, New York, Association Press, 1973. Pourmelle, Jerry (Ed.), Black Holes, New York, Fawcett, 1979. Sagan, Carl, Cosmos, New York, Random House, 1980 Stephenson, F. Richard, David H. Clark, "Ancient Astronomical Records from the Orient", Sky and Telescope, February 1977, pp. 84-91. Vehrenberg, Hans, Atlas of Deep Sky Splendors, 4th Ed., Cambridge, Massachuetts, Cambridge Univ. Press., 1983 Warner, L., Astronomy for the Southern Hemisphere, Wellington, New Zealand, A. H. & A. W. Reed, 1975. 86 PERIODICALS "Astronomical Calendar", Astronomical Workshop, Furman University, Greenville, South Carolina. "Astronomy", Astro Media Corporation, Milwaukee, Wisconsin. "Mercury", Astronomical Society of the Pacific, San Francisco, CA "Observer's Handbook", Royal Astronomical Society of Canada, Toronto, Ontario. "Scientific American", Scientific American, New York, N.Y. "Sky and Telescope", Sky Publishing Corporation, Harvard College Observatory, Cambridge, Massachusetts SOURCES Astronomical Society of the Pacific, 1290 24th Ave., San Francisco, CA 94122 Willman-Bell, Inc., PO Box 35025, Richmond, VA 23235 (major supplier of astronomical books and charts). 87 APPENDIX G BUYING A TELESCOPE If DISTANT SUNS has done its job, by now you may be saying to yourself "Self, I wonder if I should get a small telescope?" Well, what's stopping you? When you first consider buying a telescope, figure out what exactly you want to do. If you are merely interested in casual peaks at the planets, there is no need to get a $6700 Compustar 11. Or if you want to get something really portable for backpacking don't get a 17 inch Dobsonian when a good pair of binoculars might do the job. No doubt your first thought is "but I want to see everything!" Unfortunately, there are always going to be drawbacks to accept and choices to be made. Telescopes are measured in the size of their objective (either lens or mirrors). So a "17 inch" Dobsonian will contain a mirror, 17" in diameter (in other words, big). Of course the larger the diameter, the more you will see, but the draw back is that a 17" is large and heavy. Such an instrument may quickly throw water on the enthusiasm of a novice observer if it takes 3 people to more it out to the backyard. On the other end is a "typical" beginner telescope, such as a 2.4 inch refractor or 6 inch reflector from your local Sears. While easy to transport, the deep-sky objects will not be nearly as spectacular. Other things to consider would be the accessories available. The more serious instruments are naturally going to have more goodies to spend your money on, while the simpler models might not. As mentioned, the aperture is the chief method of measuring the general performance of a telescope. Scopes are simply "light buckets", so the larger the objective, the more light it can 88 capture and the sharper the image. Don't be mislead by advertisements for instruments costing only $200 but have 500 power. The "power" or enlarging capability of the telescope is likewise connected to the aperture size. The higher the power, the more spread out, or dimmer, the image will be. Also the less distinct it will be. A general rule of thumb is that the maximum usable power of a telescope is going to be 50 times its objective size in inches. Therefore a 2.4 inch refractor will be fine up to 120 power, after that you'd be fighting a loosing battle. Theoretically the scope could be pushed to 500 power, but the image would be too dim and fuzzy to be unusable. (By the way, 50 to 75 power is just right for most solar system observations, so magnification isn't everything). Figure 18. Perhaps the most familiar kind of scope is the good old "refractor", not much different than Galileo's original instrument. In its most simple form, a refractor combines a set of lenses at the front of a long tube, with an eyepiece at the other end (fig. 18). The standard scope of this type has a lens 60 millimeters in diameter (2.4 inches) and a tube about 3 feet long. Refractors are the most common small telescopes made, mass produced by several large volume vendors and usually sold in the toy sections of major stores. I would recommend staying away from these mass market instruments. While inexpensive, the optical quality is usually so poor as to make them nearly useless for anything but the largest and brightest objects. Quality manufacturers such as Meade, 89 Unitron and Pentax all make similar small refractors, but of much higher quality. These are perfect for casual viewing of the solar-system and some of the brighter deep-sky objects, but they just don't have the light gathering power to support astrophotography or serious deep-sky observations. Larger refractors are available, but once you get above 3" models, the prices become "astronomical" (sorry), not to mention the weight. Figure 19. Besides the refractors there is the "reflector", which as it;s name would suggest, uses mirrors instead of lenses (fig. 19). The most common of these, the Newtonian, was developed by Sir Isaac himself. The light enters in through the front, reflects off of the primary mirror, into the secondary back at the front and out of the eyepiece. A variation of this kind is the increasingly popular "Dobsonian-Newtonian", which sacrifices some general convenience for very low-cost instruments. Most telescopes are mounted on an"equatorial mount", which permits it to be tilted parallel to the Earth's equator. This allows the scope to track the motion of the stars in only one movement around the central axis of the mount (the diurnal motion is very significant, even at low powers, the object can drift out of the 90 view in only a minute). The Dobsonian opts for the much simpler fork "alt-azimuth" mount which sits parallel to the ground. This means that tracking the objects would require two motions instead of one. Not much effort in and of itself, but it makes automatic motor drives required for astrophotography next to impossible. If you don't think you'll try photography, a Dobsonian might just be the scope for you. The no frills Odyssey-8 and 10 inch scopes by Coulter Optical have been highly regarded, and cost less than 300 bucks. Fancier Newtonian scopes by Meade or Celestron in the same sizes are nearly 3 times as much. Figure 20. The most popular serious telescopes made today are the Catadioptrics, and are respected for their utter compactness. Known as a "Schmidt-Cassegrain" (SCT), and 8 inch instrument might be only 16 inches long, 1/3 the length of a standard Newtonian of the same diameter. The key is the folded optics as shown in fig. 20. The light enters in through a corrector lens, reflects off of the primary to a secondary on the plate and back through a hole in the primary. This places the eyepiece in the back of the scope making for easy viewing. SCT's come with a wide variety of lenses, camera mounts, tracking devices and 91 computer controls. The "typical" SCT is an 8" model, and will go for around $1000 to $1300, although sizes range from 3 1/2" on up the 14". The most common are the Celestron, Meade and Bushnell. While you're looking at all of these high-powered instruments, don't overlook the "richest-field" telescopes. These are deliberately lower power devices meant to give wider sweeping views of the sky. Normal scopes will be much too powerful to view the star clouds of Sagittarius or the larger details of the Hyadies cluster (something like investigating the Mona Lisa with an electron microscope). Richest field telescopes are very compact (the Edmund Astroscan slips over the shoulder) and generally quite inexpensive. Along the same line of thought would be a good pair of binoculars. While they don't come close to the light gathering power of an Astroscan, they can provide hours of enjoyment as you sweep across the sky lying on your back munching popcorn. You may want to think about getting a used telescope. If it is a name brand, it has already depreciated about as much as it will and so could easily be sold once you outgrow it or loose interest in the hobby. Prices will likely be 15% to 20% off new instruments. Before buying I would suggest visiting your local astronomy club. You should probably be able to find out how to get in touch with them through your local college observatory or astronomy department. Astronomy clubs periodically have "star parties" in which the members and any interested visitors spend all night observing at some remote site. From here you should be able to get hands-on experience with every conceivable type and brand of scope, as well as getting names of those who might have one for sale. Other than clubs, Sky and Telescope or Astronomy magazine will provide excellent information. Astronomy generally runs telescope buyer's guides in the October issues which should be 92 available at your local library, or from Astro-Media (address in reference list). If you are adventurous, you may want to try to make your own telescope. The astronomy department of your local community college may offer telescope making classes during the summer. The typical homemade instrument is either a 6 or 8 inch reflector, and can offer a real sense of accomplishment that buying a scope never can. 93 INDEX alignments 30, 31 altitude 8, 11 ASDG, Inc. 5, 61 Andromeda galaxy 3, 47 astronomical unit "AU" 49 auto-precess 25, 44 axis, wobble 44 azimuth 8, 11 Barnard's star 2, 43 Big-dipper 37 binary stars 37, 38 black holes 3 celestial equator 8, 22 cephid stars 39 color index 36, 59 color maps 24 conjunctions 29 constellations *names 19 *outlines 19, 21, 44 constellations of the Zodiac 51 control panel *date/time display 16 *location display 1l *rate display 12, 16, 17 *scroll arrows 10, 11 *zoom buttons 11, 12 control-panel 10, 14 coordinate systems 7 coordinates window 11 Copernicus 31 craters 57 crosshair 20, 24 dark nebulas 48 database 59 date, setting 16 94 declination 7, 8, 10, 11, 22 deep-sky legend 20 deep-sky objects 20, 48 default 19, 44 diffuse nebula 47, 48 display menu 11, 18 Distant Suns, program *starting 5 *defaults 15, 19 Doppler effect 43 double stars 37 Earth 1, 7, 21, 29, 30, 56, 57, 58 earth's rotation 7, 55 ecliptic 22, 35 elliptical galaxies 47 environment 15 epicycles 31, 32 equatorial coordinate system 8 extra data-disks 59 extras menu 11, 24 FACC 5, 61 flashcard mode 18 field-of-view 5, 11, 12, 20, 28, 62 fireball 52 galaxies 46, 47 Galileo, spacecraft 50 geocentric universe 31 globular clusters 46 Gregorian calendar 63 H-R (Hertzsprung-Russell) diagram 40, 41 heliocentric universe 31 Henry Draper "HD" catalog 38 "home" button 16 horizon coordinate system 21 horizon line 21, 22 Hyadies 46 IFF, saving to 25 irregular galaxies 47 95 Julian date 49, 48 Jupiter 2, 21, 29, 31, 33 Jupiter Effect 30 Kepler 33 landscape mode 17, 18, 19, 21, 22, 45, 56 latitude 7, 8 location display 11 local altitude 14, 22 local mode 11, 14, 17, 18, 19, 56 longitude 7, 8 lookdown 21, 29, 30, 31, 32, 33 lunar seas 57 Magellanic Clouds 3, 47 magnitude 36, 37 magnitude chart 25 markers 14, 22 Mars 21, 29, 30, 33 memory usage 14 menus 14 Mercury 21, 29, 31, 32, 33 Messier catalog 20, 48 meteor showers 51, 52 midnight sun 55 Milky-Way 2, 3, 46, 47 Milky-Way (center of) 2, 46 Mizar 37 Modes: *flashcard 18 *landscape 17, 18, 19, 21, 22, 45, 56 *local 11, 14, 17, 18, 19, 56 *planetarium 5, 9, 11, 17, 19, 22 Moon 26, 51, 54, 56, 57, 58, 62 mouse 10, 20 more extras menu 21 move 22 moving the sky: *direct center 11, 20, 24 *point and center 20, 21 96 *scroll arrows 10 *search 20, 23 names 23 Neptune 21, 29, 31, 35, 50 neutron stars 3, 39 New General Catalog 20, 46, 48 night vision 24 North Star 5, 11, 37, 44 Nova 39 occultations 35 Oort cloud 2 open clusters 46 operating hints 5, 6 oppositions 30 optical binaries 37 orbital speeds 33 Orion 47 planetary eclipses 33 planet names 29 planetarium mode 5, 9, 11, 17, 19, 22 planetary motions 29 planetary phases 35 Pleiades 2, 46 Pluto 2, 21, 29, 35 Polaris 11, 37, 44 precession 5, 25, 35, 44 precession of outlines 25, 44 printing data 25 proper motion 43 pulsars 4, 39 quasars 3 quickview 14, 21 quitting the program 17 radial velocity 43 radiant 53 rate display 12, 16, 17 real-time 17 red giant 40 97 red shift 43 redraw 15 reset 15 retrograde motions 32 right-ascension 7, 8, 10, 22, 59 Ring nebula 48 Saturn 21, 29, 31 saving the screen to IFF 25 scroll arrows 10, 11 search *by name 23 *direct 23 setting date/time/location/time-zone 15 show mag 23 sky-images 26 skylight 24 solar eclipse 27, 56 spectra 40 spectral classes 42 spectrascopic binaries 37 spiral galaxies 47 star clusters 46 star names 38 star trails 26, 45 stars 36 stellar classes 40, 42 stellar motions 43 stellar occultations 35 stellar positions 44 Sun 26, 34, 40, 54, 55, 56, 58, 62 sun rotation 54 sun spots 54 Supernova 39, 60 system menu 14 Taurus 2, 46 telescope feature 26, 30, 34 telescopes: 98 *reflector 90 *refractor 89 *Schmidt-Cassagrain 91 time, setting 16 time-zones 15, 16 titlebar 17 tracker 21, 27 twilight 27 universe, size of 1 Uranus 21, 29, 35 user data 27, 59 variable stars 38, 59 Venus 21, 29, 31, 32, 34 Voyager, spacecraft 50 what's up? 28, 49 white dwarf 40 wobble, axis 44 Yale Bright Star Catalog 28, 36, 60 zoom buttons 11, 12 99 ============================================================================ DOCS PROVIDED BY -+*+-THE SOUTHERN STAR-+*+- for M.A.A.D. ============================================================================