A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Rafal O.
Date: 2018 Nov 2, 13:25 -0700
But why should I take into account abberation if the idea behind these correction is that I know Hc for some known time (SHA0, dec0) and know star's (SHA, dec) for the sight time. As these two parameters changes slowly I can even use rules given in 'Long Term Almanac 2000-2050' by Geoffrey Kolbe. When Hc is being calculated then only (LHA, dec, Lat) are input parameters.
I tested these algorithm for about 10 different latitudes (north and south hemispheres) using large parametrs changes (like, i.e. dLat up to +/-45', for this case more reasonable is to take another latitude and use smaller dLat). During these tests I found that about 90% of Hc are calculated inside 0.3' error bars.
So, if only my approach is correct and I know (SHA, dec), hence, their changes in respect to (SHA0, dec0), I should be able to correct Hc, too. I do not provide any ways to correct Zn so far. But comparing results for the year 2050 the difference was about 1°.
Maybe I do not see the whole picture behind your question about the abberation? But if it comes into play it should be hidden in (SHA, dec) already.