------------------------------ STARVIEW by Neil Parry (C)1993 ------------------------------ IMPORTANT! ---------- You are free to distribute this program providing that all the files remain unchanged and accompany the program. StarView is a shareware program, so if you find it useful, please send £5 to the following address: Neil Parry. 35 Preston Lane, Bilton, Hull. HU11 4DE. 1. Introduction --------------- StarView is a mouse-operated program designed to show graphically the positions of the stars and planets from any point on the earth. Most stars above magnitude 4.5 are shown (over 850 in total), more than 100 with their proper names. The outlines and names of all 88 constellations are also given. Other features include zooming in/out, finding a constellation, adjusting the level of detail shown, saved preferences and the ability to print a view of the sky. The program was written using HiSoft's Power BASIC. 2. Using the program -------------------- 2.1. Entering the time and place. The 'Change Time and Place' window can be accessed by clicking on the time/place information boxes at the top of the screen. It will also be brought up automatically when the program is first run. Click in the text boxes to type in the details as follows: Date - in the format DD.MM.YYYY, any date from 1950 to 2050 is valid. Time - local time in the format HH.MM (24-clock). (If you have an internal clock, click on the NOW box and the current date and time will be entered automatically.) Zone Offset - The offset between your local time and Greenwich Mean Time, in hours. For instance, this would be 0 in Britain in winter, -1 for British Summer Time, +10 for Western Australia, etc. Latitude - of your location in degrees 0-90 followed by N or S. Longitude - of your location in degrees 0-180 followed by E or W. Both latitude and longitude can be entered with up to 2 decimal places. When finished click on EXIT, the program will calculate the star positions for the time and place you've entered. If any of the values were invalid the screen will flash and the cursor will be positioned on the value in error to allow you to correct it. If you've changed your mind click on CANCEL to return to the program. The SAVE button will save your current time & place to disk (make sure the disk isn't write-protected). These values will then be loaded up whenever the program is first run. 2.2. Horizon View and Zenith View. StarView displays the night sky in two separate views. The horizon view shows a portion of the sky from the horizon up to an altitude of 70 degrees. The zenith view shows a circular view of the sky centred around the zenith (the point in the sky directly above your head), you can view the whole sky at once in this mode. To switch between these two views, click on the icon at the bottom right of the screen (a circle or a square depending on which mode you're currently in). 2.3. Scrolling and Zooming the sky view. Horizon View: On the horizon view are scales to show the azimuth (the direction you're facing) and the altitude (the angle up from the horizon). These scales also act as scroll bars for the view. Click in one of the bars and drag up/down or left/right to scroll the view. Note that the altitude bar won't scroll when on maximum zoom-out as it is at the limit of 0-70 degrees. To zoom in or out, click on the zoom bar at the bottom left of the screen and drag left/right. Zenith View: The zenith view shows the points of the compass around the edge of the circular view, to rotate this view click on one of the compass points (or anywhere just outside the circle) and drag the pointer around to adjust the view to the angle you want. Zooming is achieved using the zoom bar, as with the horizon view. The zoom is always centred around the zenith, the number next to the zoom bar being the radius of sky currently being shown. In addition, (in either view mode) the NSEW buttons on the left of the screen can be used to centre the view on a particular compass direction. 2.4. The SetUp Menu. Clicking on the SETUP button will bring up a menu of options which allow you to adjust the level of detail shown on the sky view. The options are as follows: Constellations Identified (MAIN/MOST/ALL): Selects the number of constellations outlined and labelled on the screen, MAIN shows just the brightest or most obvious constellations, MOST shows all except the faintest and ALL displays all of them. Constellation Outlines (OFF/ON): Selects whether constellation outlines will be drawn or not. Constellation Names (OFF/ABBR/FULL): Selects how the constellation names will be displayed. FULL shows the full constellation name, ABBR shows a three letter abbreviation. Star Names (OFF/SOME/ALL): Over 100 star names are stored by the program, ALL will display all of them, SOME will just label the brightest. Planets (ON/OFF): Selects whether the planets will be shown or not. Note that the brightness of the planets is not given, just the position, and in fact the outer three planets (Uranus,Neptune & Pluto) are not actually visible with the naked eye. Star Symbols (DOT/BIG): Selects how the stars are displayed on the sky view. DOT represents a star as a single dot that can be a different brightness depending on the magnitude of the star. BIG represents brighter stars as a larger dot, which is useful when printing out the screen. 2.5. Finding a constellation. Clicking on the FIND button will bring up a list of all 88 constellations. Click on a constellation and if it is visible, the program will find it and return to the horizon or zenith view depending on where in the sky the constellation currently is. If the constellation isn't visible, NOT VISIBLE will flash at the bottom of the screen. This option also displays the abbreviations and meanings of the constellation names. 2.6. Printing the screen. Clicking on the PRINT button will print the screen. Note that this is simply a graphic screen-dump and will be printed according to the printer settings in Preferences. I've found that printing a black-and-white, negative image with a threshold value of 14 produces good results. It also helps having the star symbols set to BIG (in the Setup Menu) in order to determine the magnitudes of the stars on a black-and-white print. 2.7. Quitting the program. Click on QUIT to return to the Workbench.