NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Semi-diameter in the Nautical Almanac
From: Fred Hebard
Date: 2009 Dec 22, 08:26 -0500
From: Fred Hebard
Date: 2009 Dec 22, 08:26 -0500
If I recall correctly, you have to be about a mile away to use a telephone pole and avoid parallax. The "sanity check" is very nice because if you are consistently off, you know either your measuring technique is off or there's a maladjustment in the sextant. On Dec 22, 2009, at 7:36 AM, Gary LaPook wrote: > I like that method of checking index error because you get repeatable > results since the variations in the horizon go away. But you don't > need > to know the S.D. to do it and it really doesn't provide a "sanity > check" > all it does is give you a measure of the accuracy of the scale between > plus and minus about half a degree. This type of check can be done > with > any far away object such as a building or telephone pole, the actual > width of the object makes no difference in finding the index error. -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com