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    Re: Index Mirror Correction
    From: Wolfgang Bosswick
    Date: 2003 May 16, 09:15 +0200

    Dear Fred,

    Thanks a lot for you help. I think I have to worry the next months more about my practice to take sights than about non correctable errors of my sextant ;-). With a 0.5' error, I would be perfectly happy (currently I am usually around 1. 0' to 2.0'). Guess, I really need some more practising.


    Fred Hebard (Fred@ACF.ORG) schrieb:

    Dear Wolfgang,

    I was in a position similar to yours 5 months ago. My advice would be
    to not worry too much yet about non-adjustable sextant errors until you
    can get consistent readings with a standard error of less than 0.2' of
    arc and to within 0.5 to 0.7' of your known position (Hc - Ho < 0.5').
    (It the positions start coming in with 0.1 of your known position, then
    you will know that your sextant is pretty accurate at that angle).
    That might take more than one hundred observations of 3-6 sights each.
    You could then start to determine whether there was any systematic
    variation in (Hc - Ho) with Ho.

    George Huxtable answered your question about the distance (angle)
    between stars in a post in January,
    http://www.i-DEADLINK-com/lists/navigation/0301/0029.html. I have not
    implemented this method to a large degree, only a few tens of
    observations. I've been concentrating instead on timed observations,
    which are more relevant to practical navigation. The most difficult
    part for me has been timing the sight accurately, which is critical for

    Hope this helps,


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