NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2023 Feb 28, 06:25 -0800
There are 32 algorithms for calculating Delta-T available in Stellarium. That's nuts. Most of these are obsolete and irrelevant to any conceivable purpose. Part of the problem seems to be the belief that an algorithm is required. Algorithms are only of interest for periods before about 1960 and after the present date. No algorithm should be used for the period 1960-2023 (as of writing) since this is an observable parameter. And it is more like the daily temperature than, for example, deterministically predictable evolution of orbital elements. At least the Stellarium team did finally update the app to include an "adjusted" variant on one algorithm (originally published by Fred Espenak and Jean Meeus) that over-writes recent years with observed values. But there still seems to be a lot of confusion out there.
Can anyone find a setting in Stellarium that simply tells us the current value of Delta-T in place on any date in its computations?
Frank Reed
