NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Corrections for air bubble sextants
From: Gary LaPook
Date: 2022 Aug 1, 12:26 -0700
From: Gary LaPook
Date: 2022 Aug 1, 12:26 -0700
A good way to find the index correction of a bubble sextant is to shoot Polaris as it crosses your meridian, now at about 18:20 local STANDARD TIME and again at 06:20. These times shift earlier by two hours every month so wait a month and it should still be dark at 04:20 when Polaris will be on your meridian. See:
http://fer3.com/arc/m2.aspx/Fw-Shooting-Polaris-with-bubble-sextant-LaPook-may-2011-g16416
gl