NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2022 Mar 14, 04:56 -0700
Hello!
Yesterday I - for the first time with a bubble sextant - tried to get the Moon LoP.
I centered the Moon's limb within the bubble (made the limb concentric with bubble's outline). Then, because the air temperature was outside the tabulated values of my favourite table (approx. -10°C), I decided to rely upon the NA's A4 table along with the standard correction tables from the pages xxxiv and xxxv there.
I miserably failed in my attempt to comprehend the MOON CORRECTION TABLE instruction text. :(
The upper part of the MCT is limb-agnostic, so I fetched the +0°62,6' entry (the HA was 17°18' after the Index Correction applied).
Next I looked-up the HP (which was tabulated as 0°54,8') and got the second correction (0°01,6'+0°01,7')/2 ≈ 0°01,7'.
The ADDITIONAL REFRACTION CORRECTION FOR NON-STANDARD CONDITIONS value was equal to -0°0,3' (per 1005 hPa at -10°C).
So, I summed up 0°62,6' + 0°01,7' - 0°0,3' = +0°64,0', from which I subtracted 0°15,0'. The final correction value was +0°49,0'.
Is that the proper way to use those tables (for the Moon and bubble sextants)? I ask because that put me way off my GNSS position, I suspect gross error somewhere, so I'm checking my steps...
Warm regards,
Tony
60°N 30°E
