NavList:

Charles Vaillancourt, a couple of weeks ago, you wrote:
"Hello everyone, although I've been lurking around quite a bit these past few weeks, this is my first post on this site."

I shouldn't have to, but I will apologize for the NavList community here. I'm sorry no one replied to your post. January can be one of the quiet months. In addition, there is a natural demographic trend for a community of celestial navigators like this one... As the group ages, formerly avid celestial navigation enthusiasts often discover, "hey, I gotta get out more!" or "hey, I gotta spend more time with my grandchildren!" or "hey, let's spend the winter in southern Portugal..." All good things, but, yes, these take energy from celestial navigation discussions. :)

You wrote:
"I've been a sailor for decades but took up celestial navigation only recently and I'm finding it fascinating. I'm sure I still have a lot to learn but I was able to perform my first fix from the snowy beach at our lake house two weeks ago and I was within 2 miles (call it beginner's luck)."

Nice! I disagree that this is beginner's luck. With good background, you can achieve accuracy levels like that (from a beach) on a regular basis. Of course, there's always a little luck involved. :)

You added:
"I found the process of sight reduction to be quite tedious and lengthy and was looking for a way to make it easier and to do away with the Almanac and sight reduction tables."

We should get hats. Step one is where you are now: duplicating the normal process of site reduction with your own code. It certainly makes everything less tedious.

"I found several mobile apps and computer programs to do it, but apps imply using a GPS-equipped device to plot a celestial fix, which doesn't feel right, and I think computers are too cumbersome and fragile, so I wondered if I could program my good old HP Prime calculator to do it. It turned out that it IS possible and that it actually works quite well, but it took a LOT more effort than I ever anticipated, especially to calculate the ephemerides. I have made the source code and instructions available in this Github repository [https://github.com/placidanomaly/HPPrimeSightReduction] and I would welcome anyone to inspect, critique, and contribute to the code base."

It sounds like you have some background in coding? It's not the fact that you coded on an old HP calculator, but rather that you pointed us to a Github repository. That's like "speaking Latin" for many people in this community, so right there is another reason why your original post did not get much attention. If you're game, maybe you could describe more about your code and coding process. Where did you get your ephemeris code? How did you test your own implementation of that code? And what other items are in your app? Do you have a model for refraction? Where from? And so on...

You concluded:
"With this, I am able to plan observations, look up ephemerides, perform sight reduction and graphically plot a fix, all on the calculator, so all I need to plot a position is a sextant, a watch, and the calculator."

Ah, graphical plotting... See, this is where the traditional mathematical tools continue to constrain the way you think about celestial navigation. Break out of the box! ;) Ha ha. That's frequently the next phase for navigators who enjoy the math. 

No plotting? What?! Suppose you shoot Polaris in evening twilight, waiting carefully for that brief window when Polaris is visible and the horizon, too. You can get a latitude without much trouble from that (have to be in the latitude range 3°<Lat<65° or so, but that's a lot of important ocean!). Once you have your latitude, you immediately turn around and shoot the brightest star you can see, maybe Vega. On a calculator, you can directly get your longitude (no plotting required). Have you tried that? It's fundamental to my "Modern Celestial Navigation" workshops, as well as "Advanced" and "Expert" which follow. Much of the plotting can be skipped!

Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA