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Re: Lunar longitudes, not by lunar distance. Was- Re: Working a lunar
From: Hanno Ix
Date: 2009 Aug 7, 20:06 -0700
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From: Hanno Ix
Date: 2009 Aug 7, 20:06 -0700
Gentlemen: I got a copy of Chauvenet Vol 1,2. , 1874. In short: His goal is to establish positions of international astronomical observatories with an LAT/LOG error in the range of seconds. There is indeed an article, nr. 229, in Vol 1 where Chauvenet presents briefly the concept we are discussing here. He then goes on to describe methods to deal with a problem of his days: inaccurate ephemeris, particularly of the moon. Since he has no list of DT, as we imagine here, he subsequently describes methods of calculating DT as best he can. These methods include an approximate knowledge of GMT and position. He finally goes on with a statistical error analysis using the data of several lunations. So, I must bow to Chauvenet, or to whomever came before him. Modern navigators do not have his problems, though. Assume, a sailor has a transit instrument, a good stopwatch and an almanach that includes DT with sufficient resolution. With those tools and this method, he can find reasonable values of GMT and his position while on land, and can do so without prior knowledge of either. At least, that appears to me so at this time. The practical implemetation seems quite possible, however I have not shown that - yet! Regards, and thanks for your continued interest. H --- On Fri, 8/7/09, Brad Morris <bmorris@tactronics.com> wrote:
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