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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Another sight reduction analog device
From: Gary LaPook
Date: 2012 Apr 28, 00:32 -0700
From: Gary LaPook
Date: 2012 Apr 28, 00:32 -0700
| Basically it projected the Weems Star Altitudes Curves on to a flat surface for plotting. Since the curves were on a roll of film the device tool up a lot less room than the Weems book of curves. Both of these methods show that the determination on latitude is independent of time, the two altitude curves will always cross at the same latitude. But that intersection moves around the world at 15° 02.46' per hour so you need time to determine the location of the intersection in longitude. Another way to look at it is that crossing two LOPs provide a fix in latitude and LHA Aries and you then use time and the GHA of Aries to convert it to a longitude value. gl --- On Fri, 4/27/12, Alexandre E Eremenko <eremenko@math.purdue.edu> wrote:
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