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    Re: Sudden shift in sextant sights
    From: Bill B
    Date: 2012 Mar 28, 21:10 -0400

    On 3/28/2012 3:34 PM, Zvi wrote:
    > I went down today to Brighton Marina to take some pre-computed sights.
    > Basically I pre-compute sun altitudes for a known GPS position just
    > outside the marina for every 20 minutes, and also note the change in
    > altitude per minute for each pre-computation (for example – at 11:20
    > UTC, calculated altitude for that position was 41 29.0 and it was
    > increasing by 2.4’ per minute at that time). I then sit on the beach and
    > take 3 sights every 20 minutes as close as possible to the target time,
    > correct them according to their time difference from the target time
    > with a table I prepared, and compare them to the pre-computed calculated
    > altitude for that time (for example, I took a sight at 14:18:38 which
    > was 41 25.0 and added to it 3.3’ to ‘bring’ it to 11:20, obtaining an
    > intercept of 0.7’ away).
    Large snip
    For a refreshing change, I'll agree with Alex....
    Were it me, I would use an online calculator to reduce each observation 
    and compare that Hc to my pre-computed numbers.
    Bill B

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