SWG@MIT-XX.ARPA (S. W. Galley) (12/15/85)
(I added you to the sub-list based on Stanford's geographic position.) Welcome to the SKY-FANS distribution list. It began with primarily local recipients who wanted to see predictions for the next week that used to be printed on time-sheets posted next to local terminals. Now, the MIT-XX Batch system sends a message every Friday morning, giving a graph of predicted sun & moon rises & sets, plus the "special events" of the moon's change of phase (e.g. *1Q = first quarter) and the beginning of seasons (e.g. *SE = spring equinox). Since the sun position is calculated quite accurately, the times of sunrise & sunset (defined by the program as the time when the center of the real sun crosses the horizon) are also given to the nearest second. (All times are for the geographical position of MIT, in Eastern civil time, unless you requested predictions for some other position.) Lastly, MIT staff holidays (and certain other holidays) are shown next to the day number. Now that the list has grown, it can also be used to announce anything having to do with astronomical events. If anyone can supply algorithms to predict other worthwhile events, I may include those in the weekly message, too. The algorithms for sun & moon positions come mainly from the "Explanatory supplement to the astronomical ephemeris and the American ephemeris and nautical almanac" (1961) and the "Improved lunar ephemeris 1952-1959" (1954) from government printing offices. -------
warren@pluto.UUCP (Warren Burstein) (12/20/85)
Can you supply me with the full names of the sources for those algorithms so I could find them in a library? Do I look under U.S. Govt or what? Would it be possible to mail me the program, or the piece that covers sunrise/sunset? The last time I tried to figure this all out I was quite confused by books on spherical astronomy. Does the need to say that the definition of sunrise/sunset is "center of the sun" imply that there are others? Thanks -- The Maxwell R. Mayhem Institute for Quandary Requiem and Maternal Sciamachy Accept no substitutes.