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    Re: Latitude + Longitude @ Noon
    From: Frank Reed CT
    Date: 2005 Jun 6, 22:55 EDT

    Henry you wrote:
    "Forwarded for your further  comment is the following posting of 31 Jul
    2004, on the subject. I must say  that your failure to respond, and for
    that matter the failure of this list to  do so in general, was most
    dissappointing. I try only to post on practical  navigation matters that I
    have tried or experimented with at sea and can only  say that this list
    appears disinterested in such matters."
    
    I remember  that post and enjoyed it. I thought you made your point well.
    Don't worry too  much if a post doesn't draw follow-ups. There's no way to know
    who has read a  particular message. People take vacations from lists like this.
    And there's no  guarantee that a post will lead to a longer conversation.
    I've started a bunch  of topics just in the past few weeks that didn't go
    anywhere...
    
    Your  approach to lat/lon near noon is to do "equal altitudes" on either side
    of noon  for the longitude. This works on exactly the same principle as the
    method I  described, of course. The advantage that arises from shooting the Sun
    every five  to ten minutes is that you have more data points and so random
    "noise" tends to  average out. This is somewhat important since the rate of
    change in the Sun's  altitude is very slow near noon. A one minute of arc error in
    a measured  altitude could easily correspond to a one minute of time error in
    the estimate  of noon (and thus 15 minutes error in the longitude).
    
    -FER
    42.0N  87.7W, or 41.4N 72.1W.
    www.HistoricalAtlas.com/lunars
    
    
    

       
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