Hi Gour, Yes, I did read the information you have quoted. I agree that the Swiss Ephemeris looks useful to Stellarium and has a compatible (GPL) license.
However, as a trained research scientist I am very fussy about sources and accuracy and I would like to see at minimum a peer-reviewed paper discussing the extension of the JPL ephemeris and discussion of algorithms used both in the integration and the data compression. Thanks, Thomas On 10 May 2012 11:46, Gour <g...@atmarama.net> wrote: > On Thu, 10 May 2012 10:55:37 +0100 > Thomas Morris <tom.s.mor...@gmail.com> > wrote: > >> I share Georg's feeling on this. The Swiss Ephemeris website seems to >> be targeted towards an astrological audience rather than an >> astronomical one. > > Have you, at least, tried to read these few paragraphs: > > The Swiss Ephemeris is based upon the latest planetary and lunar > ephemeris, DE405/406, developed by NASA's Jet Propulsion Laboratory. The > original integration, DE405, covered the years 3000 BC to 3000 AD and > required 550 Mb of disk space. DE406 is a compressed version of DE405 > which requires 200 MB while maintaining a precision of better than 1 m > for the moon and 25 m for the planets. These data have been further > compressed with sophisticated compression techniques developed by > Astrodienst. The ephemeris now requires for the complete 6000 years only > 5 Mb for all planets except the Moon, and 13 Mb for the Moon. This > compressed ephemeris reproduces the JPL data with 0.001 arcseconds > precision. > > We have extended the timespan of the JPL ephemeris by numerical > integration, so that Swiss Ephemeris covers the years 5400 BC to 5400 > AD, a total of 10'800 years. For this extended timespan the ephemeris > requires 32 Mbytes of ephemeris files. > > All transformation steps from the inertial timeframe of the JPL DE406 > integration to the reference frame for astrological coordinates (true > equinox of date), all corrections like relativistic aberration, > deflection of light in the gravity field of the Sun etc. have been > performed with utmost care and precision so that the target precision of > 0.001 arcsec is maintained through all transformation steps. Never > before has such a high precision ephemeris been available to > astrologers. > > Swiss Ephemeris contains three ephemerides. The user can choose whether > he/she wants to use the original JPL DE406 data (if available at his/her > site), the compressed Swiss Ephemeris data (the default) or a built in > semianalytic theory by Steve Moshier. The Swiss Ephemeris package > switches automatically to the available best precision ephemeris > dependent on which installed ephemeris files it finds. Even without any > stored ephemeris files, using the Moshier model, planetary positions > with better than 0.1 seconds of arc precision are available (3 arcsec > for the Moon). > > > or it is just prejudice considering that astronomy & astrology does not > have anything in common? > > > Sincerely, > Gour > > -- > As a strong wind sweeps away a boat on the water, > even one of the roaming senses on which the mind > focuses can carry away a man's intelligence. > > http://atmarama.net | Hlapicina (Croatia) | GPG: 52B5C810 > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Stellarium-pubdevel mailing list > Stellarium-pubdevel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/stellarium-pubdevel > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Stellarium-pubdevel mailing list Stellarium-pubdevel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/stellarium-pubdevel
