A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: John D. Howard
Date: 2016 Nov 3, 16:52 -0700
Thanks for your reply but I think I must clear up something you said. The form you are using is correct. When you add GHA to a WEST Longitude you are adding a negative number ie you are subtracting.
LHA + EsLon 3 d + (-) 66 d 30 m = 3 d - 66 30m = -63 d 30 m.
LHA is always between 0 d and 360 d so you must "normalize" the negative LHA by adding 360 to it. ( If LHA was 425 d you would subtract 360 )
LHA = -63 d 30 m + 360 = 296 d 30 m LHA is Greater than 180 so the second rule would be used ie t = 360 - LHA
t = 360 - 296 d 30 m = 63 d 30 m
Rember LHA does not have a sign and is always 0 to 360. You must normalize if outside that range. t has a sign: negative for west or postive for east.