Any astronomers around?

[HP67]

Thanks guys.

@Everettr Yes, given a lat/long my sunrise/sunset values using the USNO algorithm match up with nearly every published source I can find. But other ephemeris I calculate based on those matching values can sometimes be off by several minutes and I haven't understood why.

I will try to see if I can get this correction you explained to line up with what I am seeing elsewhere. I appreciate the help. I don't like this solution though because it is predicated on having updates to the declination based on seasons or some period which although makes perfect sense and is probably absolutely correct, does complicate the issue for a program running on a calculator. To apply it I would need to have a table and I would have to see if it needs updating from year to year.

Thanks for the comments. Keep 'em coming if anybody has more ideas on this.