NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Huub Robroek
Date: 2023 Jul 1, 08:17 -0700
HI all
I need some help as I am not sure whether it is an interpretation error or a calc error.
First of all, I discovered a calc error in my calculations, iso 1.8˚ E, after re-calc I now get a Lon = -2.5˚, which is 2.5˚W.
Here is my data:
@21:51:05 UT: Venus: GHA = 105.5˚ Dec = 13.4˚N
Finding ZD from Ho
Hs = 1˚ 27'
Dip = -5'
Refr = -21' (based on h< 15˚, using R = 1.0' / tan[h + 6.82/(h + 4.024)] from the AdvCN Guidebook)
-----------------
Ho = 1˚01' --> ZD = 89˚ (rounded)
With Lat = 55˚ the ABC method gives:
A = 0.03128
B = 0.34023
C = -0.30895
HA = cos inv (C) = 108˚
Lon = GHA - HA = 105.5-108 = -2.5˚ = 2˚30' W
Can anyone enlighten me where I make the mistake? (the 2.5˚ looks correct, but why minus ? A coincidence, or my misinterpretation?)
Your feedback is much appreciated!
Huub
