NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Gary LaPook
Date: 2011 Feb 13, 10:43 -0800
| All I can say is "keep shoveling." The essence of the "noon sight" is that you don't know the actual time of noon in advance since your estimate is based on you DR longitude. Prior to chronometers they still used the "noon sight" for latitude even though they measured time with only a calender. If you want the exact time of LAN at your location it is easy enough for you to do with your almanac and the time should be between about 1745 Z and 1810 Z at your location as the equation of time varies during the year. To calculate this you start with the longitude of your location (you do have a gps, don't you, if not use Google Earth) and subtract the GHA of the sun from it using either 1700 or 1800 Z, whichever is less than and closest to your longitude. Take this remainder and run down the increments table until you find the time period that results in this remainder and add that time to 1700 or 1800 Z that you started with. If you just want it to a one minute accuracy so that you know approximately what time you should start standing out in the cold then you can use the time of meridian passage from the Nautical Almanac adjusted for the difference between your longitude and the longitude of the standard meridian for your time zone, 90° west in your case. Your noon should occur about 9 minutes before the listed times. For the dates you listed: Feb 19 1214 Feb 20 1214 Feb 26 1213 Feb 27 1213 Mar 5 1212 Mar 6 1211 The online almanac at tecape doesn't have this auxiliary data. gl --- On Sun, 2/13/11, Matthew G. Ashbrook <ash13brook@gmail.com> wrote:
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