# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: My lunar distance tables
From: Francis Upchurch
Date: 2014 May 18, 09:33 -0700

Hi Frank and/or other lunar experts.
Couple (ok, 3) questions for the master of lunars please.
1) I've been interested in your "short clearance method" using vertical circle "collapse". Looking at your correspondence with the sadly late George Huxtable in 2010, I wonder if you or anyone got round to doing the "quick look up table" as a check test to see if in bounds? I think your idea is totally brilliant if it can be used reasonably often.(is it only viable near the tropics? Unfortunately I am in England!)(well fortunately really in most other respects!)
2)I'm also, totally irrationally, given the multiple quartz watches aboard, interested in " no clock longitude using lunars." (mostly sun/ moon "fix" using GMT from the lunar.) I've been trying to guess the approx , no clock GMT from the lunar Sd, using my home made 3 hourly predicted LDs printed out from your excellent site.(ie a pre 1912 almanac really). Am I correct in thinking that the maximum error of an non cleared LDsd is about 60'? or have I got it completely wrong? (I guess that would still be a huge incorrect longitude?)
3) I've also been studying Raper's 1840 book on nautical astronomy (free PDF on Google.) Chichester's only text book apparently. Has a section on "approximate clearance methods using spherical traverse tables." I wonder whether you or other lunar experts have looked at this? I did a couple of clearances using these and got good ,accurate and quick results. Unlike the excellent Stark tables, I nearly understood the maths behind these travers tables. They did not appear to catch on , so maybe a problem?
As always, thanks for your help in advance and good look with the celnav course. Would love to be there but health issues prevent travel to one of my favourite (UK spelling ?) places (New England) .
Best wishes
Francis
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