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This program is designed to run on the *IBM PC and 'true' compatibles. It requires at least 256 K of memory and CGA Graphics capability or equivalent. Copyright 1987 by Ed & Stewart Vernon. All rights reserved. Ed Vernon P.O. Box 61095 Raleigh, N.C. 27661 This Program is made available to be copied and passed on to others, as long as it is copied in it's entirety and not altered in any way. It is not Public Domain. This Program is solely the property of the Author, and no remuneration may be made for it except to the Author at the address listed above. Try this program, and if you con- sider it usefull, or worthwhile, send $20, or whatever you consider it's worth, to the address listed above. In any case, pass it on to a friend to evaluate. This Program may be freely Uploaded and Downloaded to and from Bulletin Boards, and related public access facil- ities, as long as no charge is made, and all the Program is passed-on without change or modification. *Registered trademark of IBM Corporation. Page 1 Before Running this program, it is desirable to Enter the correct Time and Date into your DOS System, as the pro- gram utilizes this Time and Date initially to establish a reference. If you would like Graphic Printouts of the star maps, it will be necessary to also pre-load the Graphics function that comes with your DOS operating system. Follow the instructions that came with your system to load, and actuate the Graphics program. Page 2 ASTRONOMY Copyright 1986 by Ed & Stewart Vernon All Rights Reserved In general this Astronomy program is intended as an aid to the Amateur Astronomer or the serious student of Astro- nomy. It can draw a map of about 900 of the brightest stars for any time of the day, at any location on the Earth. It can locate all of the planets, as well as the Sun and Moon, on this map, or give you a list of their coordinates. It can outline all the 88 Constellations, and plot the path of the Sun, Moon, and Planets against the background of Stars. You can Enlarge any portion of the Starmap, and locate any point according to astronomical coordinates. A bit about Stellar Magnitudes The Greek astronomer Hipparchus first conceived the idea of dividing all visible stars into six arbitrary grades of brightness. The brightest group of about 20 stars, were cal- led first magnitude stars. Later on Ptolemy refined this method somewhat and introduced fractions of a magnitude. With the invention of the telescope, many more stars became observable, and more exact comparisons between stars were needed. Instead of opinion and guesswork, each magnitude differed from the next by a factor of 2.512 or about two and one half times. The difference between five magnitudes being equivalent to a ratio of 100 to 1. It was found that some stars were actually brighter than first magnitude, so the concept of 0, and even minus values of magnitude was introduced. For instance, Sirius, or Alpha Canis Majoris, which is the brightest star in the sky is at magnitude -1.4. Our Sun is magnitude -26.7 and our Moon is magnitude -12. However, under perfect viewing conditions, only stars to the sixth magnitude can be visible to the un- aided eye. This program contains stars to about magnitude 4.5, so there are approximately 900 that may displayed. It is impor- tant to remember that the higher the positive magnitude, the dimmer the star. Seven different symbols represent stars of seven different magnitudes. You can change the magnitudes that correspond to each symbol from it's default value if you wish. You can also change the lower magnitude limit of stars drawn on the starmap. By making the magnitude limit a lower number, correspond- ing to a brighter star, you decrease the number of stars on the display, therefore increasing the speed at which the screen is drawn. This capability is quite practical when you have to go back and forth between different starmaps and/or other screens. Page 3 Program Operation Before attempting to Run the Astronomy program, the first thing to do is make a "back-up" copy for general use. Use the "Diskcopy" function of your computer. Put the original safely away and run the back-up copy only. Type ASTRONOM and press the Enter key. You should get a Title screen, which tells you to wait while the program Data is being loaded. Generally, Upper and Lower case does not matter, and input functions for the most part are automatically limited by the Computer to the proper type and length. One case in particular where the input is not limited, is the Star Magni- tude Breakpoints. Since Magnitude values may be + or -, and different decimal values over a broad range, these numbers are not limited. You could possibly limit your Star Presen- tation to Zero Stars, by choosing extreme values here. After the Program has fully loaded, the first screen to appear is the Title Screen showing Local Co-ordinates, with an Option to Change. If 'C' to Change is pressed, the program will ask if you know your Longitude and Latitude. If 'N' for no is pressed, a World Map will be drawn. If any key other than 'N' is pressed, you will be asked to Enter each Local value at the prompts. If you don't know your Time Zone, 'O' for Other may be used for any location. Upon completion you will be asked to press 'S' to save Local Co-ordinates on disk, or any other key for Temporary use. If you selected 'N' you will get a World Map which is Cylindrical Orthomorphic, or Mercator, after the 16th Century Cartographer who invented the style. The sizes of land masses at the Poles of the Earth are exaggerated to keep longitude lines parallel. On PC type Keyboards... Arrow keys locate the crosshair, which initially appears at the approximate center of the screen. Holding Shift and pres- sing the arrow keys will move the crosshair more rapidly. On the Tandy 1000... Engaging 'Num-Lock', then using 8,6,2 & 4 on the numeric pad as up, right, down & left respectively, will facilitate the rapid crosshair movement. Press Enter when you are finished, and the screen will display the correct values of your chosen Longitude and Lati- tude, and wait for you to press a key. You then choose to save these values on Diskette, or just have them for tempor- ary use during this program run. Page 4 FUNCTION MENU The next Screen is the Function Menu, where you would have already arrived if you had not chosen to change the lo- cal coordinates. This is the Main screen, and is where the program generally returns you after each function is complet- ed. Pressing a Single Key actuates the indicated Function. A real-time clock is situated above the Menu for convenience. The Function Menu Screen looks something like the following; Astronomical Ephemeris and Planetarium (C) 1987 by Ed & Stewart Vernon All Rights Reserved (Real-Time Displayed here) F U N C T I O N M E N U A lter the local co-ordinates C hange graphics color sets 1 S et-up magnitude breakpoints U pdate current time and date D aylite saving toggle on/off L ocate one particular planet M ap of visible stars plotted P lot daily planetary motions O utlining the constellations Q uit program & return to dos Current Date is Displayed here If Daylite saving time, it is indicated here Pressing the first key in the line (which is hilited) actuates the given function. Any other key will have no ef- fect except to redraw the Menu screen. Page 5 Function MENU There are 10 Keys that perform a Function on this Screen. These Keys at the start of each line, are Hi-lited for empha- sis. You do not have to press the Enter key. The Hi-Lited Keys Function as follows: A - Alters the Local Coordinates. Current Local Stats are displayed on the screen, with a press 'C' to change capability. This is the same as the Initial screen you are greeted with. C - Change Graphics Color Sets. Will allow the user to select between 4 color sets for the graphics displays. The number of the current set is displayed on the Menu Screen. S - Set-Up Star Magnitude Breakpoints. Will list the graphic symbol for stars less than each given Magnitude, for 7 different levels, and the lower limit of magnitude for display on screen. The initial lower limit is 5, and all 900 or so stars in memory will be displayed. Press 'C' to change, or any other to return to menu is displayed. After pressing 'C' you may press 'R' to Reset all magnitudes to their original values, or press any other key to Enter New Magnitude values. Pressing any key other than 'R' will place the '<' cursor at each value to Enter. Enter a value, or just press Enter to keep the current one. The same applies to the magnitude lower lim- it. Making the magnitude lower limit smaller will display fewer stars on the screen, but the Starmap will be fin- ished sooner. There is therefore a trade-off between how thorough you wish the map, and how rapid you wish the display. For various reasons you may desire to go back and forth between several displays, and speed would then be important. After many times of this, you may then wish to display all the stars for a final judgement, or per haps for a Graphic Screen Dump. The actual speeds will depend on your particular Com- puter configuration. For instance, on the Tandy 1000 it takes 1 minute and 58 seconds to draw the complete star map, while on the PC AT, it takes 42 seconds. If you set a magnitude lower limit of 3, the Tandy 1000 takes 22 seconds to display, while the PC AT takes 8 seconds. Page 6 FUNCTION MENU (Cont) U - Update Time and Date. The current Time & Date are Updated from DOS and printed at the bottom of the Menu. The real-time clock above keeps the current time constantly, but the Time and Date at the bottom of the Menu are the 'Active' ones for Menu Functions. The Function Time and Date stay the same until you change them, in case you wish to repeat the same. D - Daylight Saving Time Toggle on and off. You may want a starmap of a date before Daylight Saving Time was conceived, or of an uncertain period. When act- ive the time is automatically compensated to allow for Daylight saving time. Pressing this also Updates the Function Time and Date. L - Locate a Particular Planet. This is the Ephemeris Function. The Planets, Sun and Moon are numerically listed for you to select one. If you just press Enter, the Sun is selected. You may then have the option of changing the Date and Time. The Time and Date will remain the same for all functions, unless you change them at an opportunity such as this, or Update from the Menu Mode. The Planet is then located, and it's distance from the Sun is printed, as well as it's rise and set times. If the selection is the Moon, no distance from the Sun is displayed, but the phase is indicated. Remember that a Planet or the Moon may actually rise in the evening or night, and set in the morning. You must then either interpret the set time as the following day, or the rise time as the previous day. M - Map of the Stars is Drawn. You first get the opportunity to change the Date and the Time. Then the Star Map is displayed according to the established magnitude breakpoints and magnitude lower limit you have previously set, or to the default values. The Date & Time is displayed in the upper left of the screen. While the Starmap is displayed you may press 'F' to get a list of the sub-functions available only from the Starmap Display Mode. Page 7 Sub-Functions from the Starmap Mode D: Displays Date and Time in the Upper left Corner. K: Writes Longitude and Latitude in Upper right Corner. C: Draws Compass Points, N,S,E and W on Screen. Z: A crosshair is drawn across the sky directly overhead locating the Zenith. E: Draws the Celestial Equator. S: Draws the Ecliptic, or apparent path of the Sun. P: Draws the Planets, Sun and Moon on the Starmap. 1-9 Draws Circles of N * 10 degrees from the Zenith. ( where N is the number pressed ) B: Lists Magnitude Breakpoints at the left side. L: Locates points on the Map in RIGHT ASCENSION and DECLINATION. Press 'L' and a crosshair appears approx in the center of the screen, with the right ascension & declination printed at the lower left. The crosshair may be moved by the arrow keys. When you are through with this Function, just press Enter. M: Magnifies an area of your choosing to fill the entire screen. As with 'L', a crosshair appears at the center and can be located with the arrow keys. This time no values for right ascension & declination are displayed on the screen. Locate the crosshair to one of the corners of the area you wish to enlarge, and press the Enter Key. A Full-Length Vertical & Horizontal line crossing at your reference point will appear on the screen, and the crosshair will re-locate back to the center. Now re-position the crosshair to be diagonally opposite from your first choice to form the total area you wish to magnify and again press Enter. Another Vert. & Horiz. line will appear, and a rectangle will outline the selected area. While the Rectangle is on the screen you may press 'K' and reset the magnitude breakpoints and magnitude lower limit. Otherwise, just press Enter and the Star map will be re-drawn magnified to your scale, and the word Magnification will appear at the top when the display is complete. While in the Magnification Mode, pressing 'R' will return to the original 'Full-size' Starmap. Pressing Enter will return to the Function Menu. N: In the Regular Mode or Magnify Mode, pressing 'N' erases the bottom line of the screen. (In case the name of a constellation is written there ...also see 'O' Sub-Function.) F: Functions Display. ( This Screen ) Page 8 Sub-Functions (Cont) R: Redo Screen and Redraw Starmap. The original Starmap is redrawn without the Date and Time, erasing all of the writing, Planets, and Cursors. However, when you select 'F' from the Starmap Mode to view these functions, whatever is on the screen at the time will become the new 'Redo' screen. Thus if you want the Redo screen to remain as the original Starmap, always press 'R' before pressing 'F' while in the Starmap Mode. O: Outline Constellations on the Current Starmap. Press 'O' from the Starmap Mode and get the list of all 88 Constellations to select from. You must enter the name of one, spelled correctly, but upper or lower case is unimportant. After typing the name and pressing Enter you will return to the Starmap screen and the selected constellation will be outlined by it's Official Boundaries, if it is located on the screen at this time. If all or part is off the screen, the words 'Plots Beyond Horizon' will appear in the upper right. You may repeat this function as many times as you like, with the previous constellations staying on the screen. The most recent constellation drawn will be named at the bottom of the screen. Pressing 'N' in the Starmap Mode will erase this name. Magnify can be selected, and Magnified Constellations may be drawn. While in the Plotting Mode Only, pressing 'A' allows the track of a second Planet to be plotted on the first in a different color. The same Date and Time, and length of Plot will be used for both Planets, however. In the Constellation Mode Only ... This is the Constellation Mode selected from the Main Menu, not from the Starmap Mode: N: Writes the Constellation name at bottom of screen. T: Writes Time the Constellation is at it's Zenith in the upper left corner of the screen. Pressing Enter leaves the Starmap & returns to the Main Menu. Page 9 MAIN MENU FUNCTIONS (Cont) P - Plots of Daily Planetary Motion. Pressing 'P' reveals a short explanation, and an oppor- tunity to abort if accidentally selected. Pressing 'P' again gives you the chance to change the Date and Time. The current Date is the first day of the Plot, and you are required to enter the number of days you want the plot to run. You must enter a value from 1 to 365. Then the Planets are listed for you to select from. Pressing a number then allows the Starmap to be drawn for the Day and Time of the first Plot. The upper left of the screen displays how many days, and which Planet you're plotting. The first plot will be a + sign, and all other plots will be small circles. The lower left portion of the screen displays the start and end Dates. As the plots are being calculated, the current plot number is also shown for your reference. It will be erased when the last plot is made. Pressing 'A' after the plot will allow you to plot another on top of the first. The Planets are again listed for your choice, then the second Planet is plotted in a different color. The name of the second Planet is printed in the upper right and the Dates in the lower right. Pressing any key will then return to the Menu. If 'A' is not selected, pressing any other key twice will return to the Main Menu. O - Outline a Particular Constellation. Pressing 'O' gives you a list of all 88 Constellations visible in the entire sky. You must enter a constellation name, spelled correctly, although upper or lower case doesn't matter. After typing the name and pressing Enter you get a chance to change the Date. Then the Time at Zenith, or the time the constellation is directly over head on this Date, is listed on the screen. You may then choose 'R' to repeat for another constellation, or 'M' to return to the Main Menu, or any other key to display your selected constellation. The constellation will be drawn as it will look when directly overhead, as the entire Starmap is now reset for this Time. Other constellations may be outlined on this map by selecting 'O' after the original outline is finished, but while the Starmap is still on the screen. Press Enter to return to the Main Menu. Copyright 1987 by Ed & Stewart Vernon All Rights Reserved Page 10 Operational Hints The Zodiac signs do not exactly correspond to their counterparts in the 88 Constellations. That is to say, the Zodiac signs do not occupy the same space as the constella- tions of the same name. The Zodiac divides the sky circle into 12 equal parts, each one being a sign taking the name of a constellation. The actual path of the Sun through the actual constellations is considerably different. It is al- most twice as long in Taurus as it is in Aries. However, for approximation, they can be used interchangably for the purposes of locating the Planets. If you wish to find a given Planet, say Jupiter, for instance, on some future date, such as April 17, in the year 2000. Use the Locate Planet Function, and set the proper date. Select the planet Jupiter, and for an Eastern United States location the screen indicates it will be 12 degrees in the Constellation Taurus along the Zodiac. Now go back to the Menu by pressing any key. Press O for out- lining the Constellations, and leave the date as is. When the screen lists the constellations, type in Taurus and press Enter. Leave the date as 4-17-2000, and the screen will indicate that on this date the constellation Taurus will be directly overhead at 10:16 in the morning. Return to the Main Menu and press M for Starmap to be drawn. Leave the date as 4-17-2000, and the time as 10:16 A.M., and after the map is finished, press P to draw the planets on the screen. You will need to watch while the planets are initially drawn, as some of them will over- write each other due to their relative closeness on the screen. You will find the Planet Jupiter is slightly out- side the actual constellation of Taurus, in Aries. How- ever, it is very close, and enabled it to be easily lo- cated. You can press O while this same screen is still on, and select Taurus to be outlined, and you can verify Jupiter is slightly to the right, in the constellation Aries. Press O again and select Aries to be outlined, and you have more proof. The Planets will often "over-write" each other as they are drawn on the screen, due to the closeness. You need to watch carefully as they are drawn, and there is always enough time between planets to recognize where each is located. Page 11 If the Planets had moved in nice smooth arcs across the sky, the ancient astronomers would have had little difficulty in devising a workable theory. Folks such as Ptolemy, Kepler, and Copernicus would have found it easy to describe the planetary motion mathematically. As it turns out in real life however, the planets do strange loop-the-loops, often going completely backward in the sky as they wander about. Of course, nowadays it is commonly known that the planets actually orbit the Sun in ellipses, and that their orbits are sometimes above, and sometimes below the plane of Suns apparent orbit. Also the inner planets move faster than the outer, and as the inner ones catch and pass the Earth, or the Earth catches and passes the outer, apparent reverse motion is observed. This loop-the-loop behavior is not readily observa- ble unless one watches over an extended period of time. Therefore most observers these days don't even notice what gave the ancient philosophers such a hard time. The Plotting Function enables you to observe this odd planetary behavior in a realistic way, without hav- ing to spend long nights out in the weather. Just press P from the Main Menu, then press P again when the veri- fication message comes on the screen. Select the Date of September 1, 1986, at 3:00 in the afternoon. Then choose 120 days as the time period. Now select the planet Venus, and watch as the starmap is first plotted, then the path of Venus over the 120- day period beginning with 9,1,1986 is plotted. The star map stands still while this is plotted, but this is a matter of practicality in presentation. In reality, of course, the stars would shift to the right each night, as the planet shifted to the left. For simplicity the stars are held still while planets path is plotted a- gainst their backdrop, the relative location between the two being accurate just the same. The time of 3:00 is accurate only for the first day, however. Notice the loop path formed as Venus appears to stop, back up, and curve upward then continue on it's forward motion. If you now press A, you can plot an- other planet's path on top of the path of Venus. You must use the same date and time, but you should now choose the Planet Mercury. Watch as the path of Mer- cury is plotted in a different color, and covers a longer distance for the same time period. For this period the path of Mercury forms a sort of Z as it does a double loop. Page 12 When in the starmap mode and you press either the sub-function E for the Celestial Equator or S for the Ecliptic, the screen may appear to pause for a while. This is a normal occurrence, and is no reason to be alarmed. Both these curves are plotted on the screen referenced to the first point in Aries. As they pass off the screen to the left, or even start off to the left, the data must be "chewed-up" to again start at the right side of the screen. This "chewing-up" takes a few seconds, and the screen appears to pause. RIGHT ASCENSION is the celestial equivalent to Longi- tude, and is measured in Hours, Minutes and Seconds, starting at the first point in Aries. DECLINATION is the celestial equivalent to Latitude, and is measured in Degrees North or South of the celestial Equator. The CELESTIAL EQUATOR is simply the Earth's Equator projected on to the celestial sphere overhead. SIDEREAL TIME is the time reckoned according to the sphere of the stars, or startime. The sidereal time is the difference between the first point of Aries and the observer's longitude projected into the sphere of the heavens. The ECLIPTIC is the approximate path of the Sun thru the celestial sphere. All the planets and the Moon, follow this path fairly closely. ZENITH is the point in the sky directly overhead. The FIRST POINT of ARIES is the position of the Sun as it crosses over the celestial equator at the time of the Vernal (Spring) Equinox. LONGITUDE is measured in Degrees East or West of a line passing through Greenwich England and the Poles of the Earth. (Max 180 Deg) LATITUDE is measured in Degrees North or South of the Earth's Equator. (Max 90 Deg) Page 13 FUNCTIONS AVAILABLE FROM THE STARMAP SCREEN D - Date and Time in the upper left corner of the screen K - Longitude and Latitude printed in upper right C - Compass points N, S, E, and W drawn on the screen Z - Zenith cursor, lines North to South & East to West E - Draws celestial equator on the screen S - Draws the path of the ecliptic on the screen P - Draws the Planets, Sun and Moon on the screen 1-9 Circles N * 10 degrees from Zenith are drawn B - Lists Mag breakpoints at the left side of the screen L - Locate points in Right Ascension and Declination M - Magnify an area of the screen N - Erases the bottom line of the screen F - Functions Display ( This set of Fumctions ) R - Redraw original starmap screen O - Outline Constellation on this starmap In Plotting Mode Only A - Plots another Planet, Sun or Moon on the same screen In Constellation Mode N - Prints Constellation Name at the bottom of screen T - Time Constellation at Zenith printed in Upper Left (C) 1987 by Ed & Stewart Vernon All Rights Reserved Page 14 INDEX Item Page ------------------------------------------------------------- "back-up" ................................................. 4 Alters the Local Coordinates .............................. 6 Change Graphics Color Sets ................................ 6 Constellation ............................................ 10 Daylight Saving Time Toggle on and off .................... 7 DECLINATION ............................................... 8 Ephemeris ................................................. 7 FUNCTION MENU ............................................. 5 Hipparchus ................................................ 3 Locate a Particular Planet ................................ 7 Magnification ............................................. 8 Magnitudes ............................................. 3, 6 Map of the Stars .......................................... 7 Operation ................................................. 4 Operational Hints ........................................ 11 Outline a Particular Constellation ....................... 10 Outline Constellations .................................... 9 Plots of Daily Planetary Motion .......................... 10 Ptolemy ................................................... 3 Redo ...................................................... 9 RIGHT ASCENSION ........................................... 8 Set-Up Star Magnitude Breakpoints ......................... 6 Starmap ................................................... 7 Sub-Functions from the Starmap Mode ....................... 8 Update Time and Date ...................................... 7 Zodiac ................................................... 11