NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Computer generated Almanac
From: Johan Linn�r
Date: 2003 Sep 8, 15:57 +0200
From: Johan Linn�r
Date: 2003 Sep 8, 15:57 +0200
Vic Fraenckel wrote: > Loath as SOME users of this list are to introducing computers into celestial > navigation, I would like to find someone that has used the "JPL Planetary > and Lunar Ephemerides" data to actually produce a computer almanac. I would > like to do so but am not sure how to proceed. I am NOT interested in getting > the data via the many excellent Web based systems as accessing the web is > NOT practical while at sea. > > Any enlightenment will be appreciated. In the mid 90-ies I used the JPL tables together with Novas-C (from http://aa.usno.navy.mil ) but an older version than the current one. With a little help of a small program from a polish astronomer (can't remember the name) I had good success in making the same data as the Nautical Almanac. The project came to a halt when I needed to focus on studies, and I also had some troubles making a good looking printout of the data (I wanted it to look like the pages in the NA). The whole idea was to make printouts available on the web in the form of pdf-files or something for about a month at a time. Thus letting cruisers who wanted to use the tables download them and print them out at any internet caf? in the world for the months they needed. I even thought of making the tables available through fax. I haven't even looked at it for a few years. I used C as programming language and the operating system is GNU/Linux. It is probably not critical as all the output was text. I have also recreated tha data in condensed Ageton tables and even tried my hand at H.O. 249 Selected Stars with some success. I keep wondering about the copyright of the design of the NA and such publications - none is mentioned in the paper volumes I have. I hope this has enlightened you, or at least helped you see the light at the end of the tunnel. I can find the code I used if you need more help. /johan --