NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Index Mirror Correction
From: Fred Hebard
Date: 2003 May 15, 09:06 -0400
From: Fred Hebard
Date: 2003 May 15, 09:06 -0400
Dear Wolfgang, I was in a position similar to yours 5 months ago. My advice would be to not worry too much yet about non-adjustable sextant errors until you can get consistent readings with a standard error of less than 0.2' of arc and to within 0.5 to 0.7' of your known position (Hc - Ho < 0.5'). (It the positions start coming in with 0.1 of your known position, then you will know that your sextant is pretty accurate at that angle). That might take more than one hundred observations of 3-6 sights each. You could then start to determine whether there was any systematic variation in (Hc - Ho) with Ho. George Huxtable answered your question about the distance (angle) between stars in a post in January, http://www.i-DEADLINK-com/lists/navigation/0301/0029.html. I have not implemented this method to a large degree, only a few tens of observations. I've been concentrating instead on timed observations, which are more relevant to practical navigation. The most difficult part for me has been timing the sight accurately, which is critical for accuracy. Hope this helps, Fred