NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Antoine Couëtte
Date: 2025 Dec 5, 10:37 -0800
while flying the A7(E) CORSAIR II at NAS Cecil Field FL, I derived the math computation in polar coordinates in the summer of 1981, simply looking for the point having the minimum of the square distances to all the LOP's, each one considered with its own confidence factor if felt necessary (any number of LOP's). Dr Jerry Alderman, then having a Contract with the US Navy at NAS Cecil Field helped me for the early part of the computations while I subsequently decided to add the very useful information on LOP's dispersion.
I have then been running what subsequently became a big software package (including Lunars, as well as a full internally built-in Ephemeris for Sun, Moon, 85 Navigation Stars and all 8 Planets [much] more accurate than NAL over many centuries - up to 2 millenia around Y2K actually - initially on the HP 41, then on the HP41CY Emulator running on the HP48GX, as well as on the Emu41 HP41 Emulator on my Desktop Computer, with the latter running up to 800 times faster than the old HP41.
While solving for Lunars on handhelds might exceed one full hour of computing time under extreme cases, thanks to its adequate computing speed Emu41 is a magic tool to play with Lunars and even Occultations since this software fully accommodates all their inherent non linear characteristics (not being the case for all Lunar Calculators).
And of course historical Lunars such as these ones can be studied and results compared with other Lunar Calculators.
Last but not least, I always aimed at having a "Vertical Format" Handheld Calculator for all my CelNav Computations at sea including "unlimited" time span validity internal ephemeris at least as accurate as NAL. And the "supercharged" versions of the HP41 and mostly HP48GX fulfill if not [far] exceed that requirement.
Kermit






