NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Latitude by Lunar Distance
From: Frank Reed CT
Date: 2006 Oct 07, 17:09 -0700
From: Frank Reed CT
Date: 2006 Oct 07, 17:09 -0700
Hi Peter, you wrote: "Here are the calculated OBSERVED altitudes and azimuths of the stars and the Moon. The distances between the bodies has then been calculated. At Lat N38d, Lon W70d, on 11 Oct 2006 (at sea): GMT Body Azimuth Altitude 6h 36m Aldebaran 134.62d 62.06d Moon(Centre) 110.68 67.34 Distance between bodies 11.41d 6h 39m Pollux 79.04d 34.18d Moon(Centre) 111.62 67.88 Distance between bodies 38.47d (Frank's distances were 11d 39.9m and 38d 13.1m) " First, you calculated the altitudes and azimuths at the DR. The final fix is quite some distance from the DR. Second, you are apparently working only to the nearest 0.01 degrees. That's much too coarse. You should re-do the calculations working to the nearest 0.0001 degrees. Then differences of 0.1 minutes of arc are much more likely to be correct. Also, please note that the observed distances I quoted (and yes, they ARE correct) were distances from the Moon's limb to the star, not the Moon's center. And you wrote: "As would be expected. The small differences are thought to be due to parallax and refraction, not the change in position. How can position be determined from these observations? " Ah, but Peter, the difference in parallax IS due to a change in position. That's why this works. :-) -FER --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---