NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Precision of lunars
From: Alexandre Eremenko
Date: 2007 Apr 15, 10:18 -0700
From: Alexandre Eremenko
Date: 2007 Apr 15, 10:18 -0700
Observations in March-April 2007. SNO-T from my balcony IC=-0.5 (constant, measured at least once a day). Reduction with Frank's calculator, temperature and pressure was taken into account. No correction was used for prizmaticity of filters; after a careful investigation it was found to be less than 0.15' for all filter combinations. The IC actually varies a little, but this variation seems to depend on the method of measuring IC, rather than on time. 3 or 4 years of experience with this sextant show that IC remains constant unless I transport it by car, train or airplane, or do some adjustment. Using different methods I always obtain IC between -0.4 and -0.6 so I use the average. I post ALL my observations from March 20 till now, not trying to choose the best or the worst or "typical". Total 85 shots of lunar distances in 20 series (usually 4-6 each). Average error over all shots is 0.07 (thus the systematic bias seems negligible). Sigma over all shots is 0.26. Error distribution for individual shots: 41 with error less than 0.1 19 with error in the interval (0.1-0.2) 11 with error in the interval (0.2-0.3) 5 with error in the interval (0.3-0.4) 7 with error in the interval (0.4-0.5) 2 with error in the interval (0.5-0.6) (of the total of 85) Error distribution of series: 10 with error less than 0.1 4 with error 0.1-0.2 5 with error 0.2-0.3 1 with error 0.2-0.4. (of the total of 20 series) Here is the list of all series: April 13, Sun at 53d: 0.1, -0.2, -0.5, -0.3, -0.3; aver=-0.24, sigma=0.22 0.1, 0.0, 0.0, 0.0, 0.2; aver= 0.06, sigma=0.1 April 3, Aldebaran at 126d (full Moon, too bright, was not sure about the correct limb): 0.4, 0.3, 0.2, 0.3, 0.2; aver=0.28 sigma=0.08 0.3, 0.6, 0.4, -0.2, 0.6, 0.4, 0.8; aver=0.4, sigma=0.3 April 3, Pollux at 73d: 0.0, -0.1, -0.1, -0.1; aver=-0.07, sigma=0.05 April 2, Venus at 137d: 0.3, 0.0, 0.5, 0.4; aver=0.3, sigma=0.2 0.3, 0.2, 0.5, 0.2; aver=0.3, sigma=0.14 0.0, 0.0; aver=0.0, sigma=0.0 0.1, 0.0, 0.1. aver=0.06, sigma=0.06 April 2, Aldebaran at 115d: 0.1, 0.1, 0.1, -0.3, 0.2, 0.0; aver=0.03, sigma=0.17 March 29, Sun at 139d (limit of sextant scale!) 0.4, -0.5, 0.1, -0.5, -0.1; aver=-0.12, sigma=0.4 March 29, Venus at 102d: 0.0, 0.1, 0.1, -0.1, 0.3; aver=0.08, sigma=0.15 March 29, Saturn at 10d: -0.1, 0.1, 0.1, 0.3, 0.1, 0.3. aver=0.13, sigma=0.15 March 29 Aldebaran at 79d 0.2, 0.0, -0.1, 0.2 aver=0.07, sigma=0.15 March 26, Venus at 70d: -0.2, 0.1, 0.1; aver=0.0, sigma=0.17 0.0, 0.1, 0.2, -0.2; aver=0.0, sigma=0.17 March 26, Aldebaran at 42d: -0.2, -0.1, -0.5; aver=-0.26, sigma=0.2 March 25, Venus at 58d: -0.2 aver=0.2 March 21, Venus at 7d: 0.1, 0.2, 0.2; aver=0.16, sigma=0.06 March 21, Aldebaran at 30d: -0.1, -0.2, 0.2, 0.1, -0.5, 0.0; aver=-0.08, sigma=0.24 Alex. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---