SILICON SKY Version 2.0 Larry Adkins I. Introduction Silicon Sky is a program which turns your $3,000 IBM computer into a $3.50 planisphere! Actually, SILICON SKY does a lot more than your garden variety planisphere. SILICON SKY displays a quite realistic representation of the celestial as seen from any latitude on earth for any date and looking in any direction. The program will display the location of the sun, moon and planets and will show the correct phase of the moon. Finally, it identifies the constellations visible on the screen by marking out their boundaries. Instructions for use are given in the following sections. II. Initialization SILICON SKY should work on any IBM or IBM compatible with either a color graphics (CGA) or an enhanced graphics (EGA) adaptor card. However, you must first initialize the program. The program comes in two versions labeled "Sisky87" and "SiSky86". SiSky87 is for those with a math coprocessor chip; if you do not have such a chip then you must use Sisky86. To initialize the program type either "INIT87" or "INIT86", depending on which version you are using, and hit return. The initialization program will ask you whether you have an EGA or CGA graphics card, the name of your default observing site (up to 30 letters), the latitude of your default observing site, the time zone of the default observing site, and whether or not you want to hear "Cricket" sounds. Cricket sounds occur after sundown when the program is operated in the PERODIC mode (see below). I would suggest that you try it with crickets sounds at first. If you find them annoying simply re-run "INIT86" or "INIT87" and turn them off. The disk is released with the following defaults: Graphics Card: EGA Default Observing Site: SOUTHERN CALIFORNIA Default Latitude: 34 degrees Time Zone: 8 (PST) Cricket Sounds: No III. Running SILICON SKY To run SILICON SKY type "GO87" if you are using SiSky87 or simply "GO" if you don't, and hit the return. You will see a screen with the SILICON SKY logo and the words "STAR DATA LOADING". This will take from 15 seconds to 30 seconds, depending on whether you are loading from a hard disk or a floppy (floppies take longer). Note: the program reads information from the disk from time to time during execution; therefore, the disk must remain in the drive (or be on a hard disk) while the program is running. MODE SELECTION After the star data has been loaded you will be offered two options: 1. SKY FOR A SPECIFIC DATE 2. PERIODIC UPDATES AT SPECIFIED TIME INTERVALS If you select the first option, one screen will be displayed for the particular date and time you specify. To see another date and time you will have to enter new data. The PERODIC mode, on the other hand, will display a sequence of screens at an interval you select, beginning with a specified date and time. If you are running the program for the first time, I would suggest starting with option 1. LATITUDE SELECTION The next option is latitude. Two options are available here, the default location selected during initialization or some other latitude. Any other latitude on Earth will work from -90 to +90. If a latitude other than the default has been selected, you will need to hit the enter key after typing in the numbers. DIRECTION OF OBSERVATION The next screen prompts for direction of observation - north, south, east, or west. After one direction has been selected, you will be prompted for date and time data. If a latitude other than the default has been selected the program will prompt you for a time zone from -12 to +12 (Greenwich is 0). TIME FUNCTIONS Finally, the program asks for observing time - year, month, day and hour. Remember to input the month as a number and the hour as a number from 0 to 24. If you are at any latitude other than the default you will be asked for the time zone. PROGRAM EXECUTION The sky will now be plotted on the screen. When the plotting is finished there will be a line at the bottom representing the horizon and curved lines at the top representing the top of the celestial sphere. The display is roughly the field of vision the average person would have looking at the horizon. How long this takes will depend on your system. A "plain vanilla" IBM PC without a math coprocessor will take about 20 seconds to paint the stars on the screen for most horizons. It will take an additional 40 seconds or so for the program to examine all of the stars in the data file. Thus, after the program begins to run it will be about one minute before it is ready to accept new instructions. If you have a math coprocessor or an AT the execution time reduces to a mere seven seconds! SCREEN MENU After the stars have been plotted, a menu will appear at the bottom of the screen. Any option on the menu can be accessed simply by pressing the appropriate number. For example, first option simply removes the menu. Thus, pressing "1" will result in an unadorned display of the sky. ----THE MENU CAN ALWAYS BE RE-ACCESSED BY PRESSING---- ---- THE "ESC" KEY ---- The options and their functions are as follows: 1. REMOVE MENU: Shows sky without menu. 2. OPTIONS: Input new data (latitude, date, viewpoint. 3. SOLAR DATA: Displays coordinates of sun, moon and planets along with date and time data. 4. CONSTELLATIONS: Displays constellations visible in the CENTRAL AREA of the screen. The selection of a particular constellation will plot its boundaries on the display, along with its name. The name can be toggled off with the F1 function key.[Note: DATA IS AVAILABLE FOR ONLY 50 CONSTELLATIONS AT PRESENT] 5. PLANETS: Identifies solar system objects. The sun and moon are labeled. Planets are identified by a circle drawn around them. 6. SCROLL: This feature allows you to scroll around the celestial sphere. Pressing the appropriate arrow allows you to scroll 360 degrees around the horizon or up from the horizon to overhead. 7. MOON: This gives a close up of the moon, showing the orientation of the bright limb across the major maria (the dark surface features). 9. RETURN TO DOS: Terminates the program.  IV. Updates This program is being distributed as shareware, and it is requested that you register your copy by sending $10.00 to the address below. Payment of the registration fee will entitle you to the next upgrade. With this version (2.0) the number of constellations on the data file is up to 50. I hope to have the constellation count completed by the next version. I also plan to include -- Coordinates -- Deep Sky Objects -- Milky Way Boundaries -- A more detailed manual Please send registration fee to : Larry Adkins 17652 Wellington Ave. Tustin, CA 92680