Re: [guide-user] Attn: Bill

Bill J Gray Oct 17 8:39 AM

Hi Stephen,

Still digging in to this. The page you reference has moved, by the
way, to http://nssdc.gsfc.nasa.gov/planetary/factsheet/jupiterfact.html
and similarly for Saturn, etc.

That page references

http://nssdc.gsfc.nasa.gov/planetary/factsheet/fact_notes.html

which says the data comes from the _Astronomical Almanac 2000_,
p. E3. The data in Guide came from JPL data, which can now be found
at http://ssd.jpl.nasa.gov/phys_props_planets.html . This references
the _Explanatory Supplement to the Astronomical Almanac_, 1992, p.706
(actually 704, but sure enough, the reference does specify sidereal,
not tropical.)

My guess would be that you're right, since your reference gives
data for both tropical and sidereal, while the JPL folks just give
the sidereal data. I hope to puzzle this out for the next update and
then send an e-mail to the folks at one site or the other. (And,
perhaps, copy in some of the NSSDC data to Guide's data. This is
a simple matter of editing the 'planets.not' text file. Not a tough
thing to fix; just a tough thing to figure out which data is correct.)

-- Bill