The U. S. Naval Observatory annually produces a book that tells the positions of all the major celestial objects for the year of publication. It was formerly titled The Ephemeris and Nautical Almanac, but a few years ago its name changed to The Astronomical Almanac. To die-hards it is still the “Ephemeris”.
With that in mind, you can appreciate the audacity of a programmer who dares to call his/her creation by that name. In addition, the output of the program is claimed to be accurate for a 100 year spread from 1920 to 2020. The U. S. Naval Observatory has to update its calculations on a daily basis!
The astronomers at Mount Palomar probably don’t use this program and a Timex computer to make cosmological discoveries. But the backyard astronomer can use “Ephemeris V” to unravel the mysteries of the night sky with an accuracy better than many planetarium projectors.
The program begins by asking the user to identify his or her place in time and Space: latitude, longitude, date, and local (24 hour) time. A thoughtful reminder prompts you to subtract an hour for Daylight Savings Time. Since “Ephemeris V” is advertised as a planet finder, the first choice you make is which planet to locate. The most prominent planet as spring 1986 began was Venus.
The planet menu clears, and a nicely organized table of information takes its place. This table summarizes the initial entries, the current phase of the Moon, the observer’s sidereal (star) time, and the constellation in which the planet is found. It tells you how to find Venus in three different languages. For astronomers, there are equatorial coordinates (right ascension and declination); for navigators, horizon coordinates (altitude and azimuth); for the novice observer, plain English (direction and height).
The next screen lets the user select a variety of different observing conditions, objects to observe, or, most impressive, the originally chosen planet graphically displayed in a computer generated “sky”. A short machine code routine paints the screen black, and a fifty degree spread of the “ecliptic”, the plane of the solar system, is plotted. The constellations are identified by name, and a flashing “0” Shows the position of the planet in question.
“Ephemeris V” is the only T/S 1000 astronomy program I have (out of about 16) which bothers to create white “stars” in a black “sky”. Use it to amaze your friends. You don’t have to know very much astronomy to know more than your next door neighbor. You might well ask, “Will I be able to distinguish the real planets from the real stars in the real sky when I use ‘Ephemeris V’?” Surely. Mother never told you, “Twinkle, twinkle, little planet,” did she?
“Ephemeris V” is available from Robotec, Inc., 59 C Street, Ampoint Industrial Park, Perrysburg, OH 43551.. Works on the 16K TS-1000, 2ZX-81, and TS-1500. Price: $14.95.