A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2016 Oct 13, 16:58 -0700
Axcel. John H and Gary L are correct. It really is horses for courses. I shot celestial for 13 years, and I don’t remember anyone ever mentioning V corrections. If they did, I must have been asleep that day. Mind you, we were using the “Air Almanac” which has ten minute values of GHA and declination, and I had four other guys to make sure I shot on a ten minute time, so I rarely had to convert arc to time or vice versa.
I think you’re worrying unnecessarily. As John hints, a 0.25 minute of arc error in GHA doesn’t correspond to a 4nm position line (PL) error at the Equator.
Off the top of my head, 1 degree error in GHA would correspond to 60nm East or West error in a PL at the Equator.
Therefore, one minute of arc error in GHA would correspond to 1nm E-W error in the same PL, and 0.25 minutes of arc would correspond to 0.25nm E-W error.
As the latitude increases the error in nm from ignoring V correction will be less, and the further away the azimuth is from E or W the effect of any particular error on the observer’s position will be less. If we ended a celestial exercise within 3nm of our declared finishing point, we thought we were doing pretty well, but it really is horses for courses. DaveP