A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Glen Swanson
Date: 2021 Mar 10, 11:47 +0100
I’m finding the discussion regarding the Celesticomp V software and the Sharp PC 1270 very interesting as over the last few weeks, in our restricted movement and shear boredom of lockdown I was rooting through some old boxes in the house and found my Radio Shack TRS-80 PC-2 Pocket Computer (a rebranded Sharp PC-1500)!
I bought this little device back in the early 80’s after wandering into a Radio Shack shop in Oakland California, looking for a programmable calculator to help me along with my astro navigation. I had been fumbling and bumbling our sail down from Vancouver Island and found myself making a number of silly errors, more as a result of rough seas and novice knowledge at the sextant and its subsequent calculations. So, the idea of a programmable calculator seemed to be the solution.
A nice afternoon chat with a very supportive sales rep helped lighten my wallet of about 200 USD, a few manuals on basic programming and a memory expansion chip that brought my PC up from 2K of RAM to the astonishing level of 6K (those of us from a certain vintage will recall when personal computers were measure in K, and not megs and gigs!). Anyway, the very basic BASIC programme I wrote worked a treat. I still needed the almanac, but the sight reductions became a breeze.
Now having re-found this 37-year-old pocket pc and being absolutely delighted to have it turn on, I decided to revisit those old days and dug around further and found a later acquisition of Mike Harris’ Astro Navigation by Pocket Computer. This is seriously leaps beyond my primate efforts and I have now dutifully typed in the lines and lines of code and seem to have it working very well with the examples using the book and a few vintage problems I’ve found here and there. Unfortunately, the examples are all for the late 1980s and while I appreciate, I can easily do all this and more with an iPad app or with on-line programmes, I’m enjoying my reacquaintance with my old Pocket PC.
But now the issues: I’m turning to the group as I’m stumped at how to update and bring Harris’ programme into the current millennium.
Specifically, the programme requires four updated variables to be entered each new year. These include N. P. Q. R.
N is no problem, as its simply the current year.
But for the life of me I can’t seem to find any information about updates for the other three variables, (P Q R). I understand that R is an annual update coefficient for Aries and P and Q are update coefficient for the Sun. And while Harris’ book -though published in 1989- was foresighted enough to give a table to update from 1988 through to 2010, unfortunately I can’t find any updates for our current date, nor for a few years beyond. It probably doesn’t help that I’m clinging to a rudimentary understanding of mathematics and celestial navigation to fully understand what Sun and Aries coefficients are in fact correcting, and with that lack of knowledge, I’m just fumbling across the ethereal finding no information on these numbers.
But I’m sure some of the greybeards of the group will possible be able to help me with this information, and if so, I’d be tremendously grateful (and for perhaps a moment or two, a little wiser).