NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Calibrating bubble sextants
From: Gary LaPook
Date: 2009 Dec 27, 14:07 -0800
From: Gary LaPook
Date: 2009 Dec 27, 14:07 -0800
For those who need to check the index error on their bubble sextants now is a good time of the year to do it. I have written before recommending the use of Polaris as it crosses the meridian since its altitude doesn't change for a considerable period of time. At this time of the year Polaris is on your meridian at the convenient hour of about eight p.m. For more information see my prior posts at: http://groups.google.com/group/navlist/browse_thread/thread/524a9eca071d603c/8a202e27fa6c7216?hl=en Here is a link to a table of declination and GHA Polaris which includes the last column (TUC) showing the time Polaris crosses the Greenwich meridian. You can use it to calculate when it crosses your meridian. For December 2009: http://www.cadastral.com/2009dec.htm For January 2010 and for the rest of 2010: http://www.cadastral.com/2010jan.htm gl -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com
