NavList:

I would like to add a couple of suggestions to the excellent ones which have been posted already. Since you wrote: “I'm looking for a sun shot program for the HP 48GX or the HP 41C”,  I’ve assumed that ideally you would prefer to use a program already written, which would allow you to input your sextant sights and perform all sight reductions for you.  If  this is the case, these are two alternatives for the calculators you mentioned:

A Navigation Pac module was produced by Hewlett-Packard for HP41C line of calculators. It was supplied as a hardware module to be inserted in one of the calculator’s four ports. I believe its programs were written by Kenneth Newcomer, who cowrote "The Calculator Afloat - a mariner's guide to the electronic calculator" (Naval Institute Press, 1980), with Captain Henry Shufeldt. Two HP 41 calculators with an installed Navigation Pac module are currently being listed for sale on eBay as I write this. You may wish to look at the manual here: https://literature.hpcalc.org/community/hp41-pac-navigation-en.pdf.  I’ve used a few of these programs in my HP41CX, after taking Frank Reeds’s celestial navigation courses, and wasn't surprised to obtain results equivalent to those of my non-programmed calculations using an HP 42 clone by Swiss Micros (DM 42). As Geoff Hitchcox wrote, programs written for the HP41 the HP42 are mutually compatible.

Some celestial navigation program for the HP48 line of calculators are listed on the HPcalc.org website, and they are available for download free of charge here: https://www.hpcalc.org/authors/762.  They were written by Thomas Metcalf. I’m unfamiliar with the author or his programs. I haven't downloaded them for use in my HP48GX, but they seem well worth trying out, and plan to do so in the future. You might wish to experiment with them, as the price is right.

Best regards, Rafael C.