A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Francis Upchurch
Date: 2015 May 15, 07:59 -0700
Question for I think Hanno +/-Greg.
Could the Doniol method be adapted for the Time sight reduction? I've been playing around with Fuller slide rule using the cosine formula
cos(LHA)=[sin(alt) - sin(dec)·sin(lat)]/[cos(dec)·cos(lat)].
Works fine but takes longer than LOP (Hc) using Bygrave or Brown-Nassau.
I like the old 19th century methods using trig logs and haversines, the formula I have is hav.LAT=logsec.lat+logcsc.p+logcos.s+logsin(s-alt). where p=polar dist and s=1/2sum. I would be interested to know if Doniol could do it?