Next message: Frank Reed: "Re: Lunar-distance almanac errors [was; The Online Nautical Almanac- beware!]"
George H wrote:
"Roughly speaking, that's ±5 arc-sec, which is compatible with my chosen
rounding-off of display to 0.1 arc-min. So I don't claim any higher accuracy than
that rounding.
There are additional errors due to some simplifications. For example, I
consider only the 18.6 year term in the nutation correction and ignore the rest.
But that contribution to error is expected to be small."
OK, well, in the event that you do not want to add this additional source of
error (every little tenth of a minute counts!) to your historical lunars
analyses, you may want to know that my online star positions are accurate to better
than one arcsecond (less than 0.2 arcseconds error). I allow the Moon's
position to vary from the JPL ephemerides by as much as 1 arcsecond, so predicted
lunar distances are accurate to 1 arcsecond.
Online Lunars Almanac, Online Nautical Almanac:
http://www.HistoricalAtlas.com/lunars/
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
