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Re: LAN at higher lattitudes
From: Chuck Taylor
Date: 2004 Jan 8, 14:36 -0800
From: Chuck Taylor
Date: 2004 Jan 8, 14:36 -0800
--- Murray Campbell wrote: > > My beginner question is what the practical limits > are for measuring altitudes accurately at high > lattitudes? > If the sun is above the horizon is it always useable > or is it best (and more accurate) to switch to a > body higher in the northern sky? If the body is lower than about 15 degrees, and the temperature and barometric pressure differ significantly from 50 degrees Fahrenheit (10 degrees Celsius) and 1010 millibars, then you would do well to apply T&B corrections. The table is near the front of the Nautical Almanac and its use is described in Bowditch and Dutton's, among other places. This adjusts your correction for refraction for "non-standard" conditions. By the way, in the Northern Hemisphere between the September and March equinoxes, the maximum altitude of the Sun is given by 90 - (latitude) - (declination of the Sun) At your latitude (52 N), the Sun does not reach 15 degrees in altitude at the winter solstice. Chuck Taylor 47 d 55.2' N 122 d 11.2' W __________________________________ Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing. http://photos.yahoo.com/