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    Re: Making an artificial horizon, and leveling thereof
    From: Alan S
    Date: 2011 Jan 23, 15:32 -0800

    George Huxtable wrote, see below, re my efforts at sun shots with the AH, the following. I assume he would like to see some of the poorer results I obtained.

    Some study of those worse results, rather than his ones that show the least
    discrepancy, may be productive. I suggest that Alan posts to the list an
    example or two of such reflected Sun altitudes, those that show
    discrepancies of a few arc-minutes (= miles), providing the following
    information-

    Date and time (to the second), sextant reading, index error, which limb
    used, and observer's position, according to GPS or map. If temperatures and
    pressures were recorded, so much the better, but unless those values were
    extreme, or the Sun was low, they will have little effect.

    Observer's position, GPS coordinates from which I've dropped tenths of a minute was 40 D 34 M North x 80 D 02 M West. No watch error. Index error's as noted. Lower limb shot in all cases. No extremes of either temperature or pressure so far as I remember.

    Date WT Hs Index Error
    19 Aug 2010 16-52-39 72D 42.6M 2.5 M On
    19 Aug 2010 11-12-22 99D 18,4M 2.5 M On
    9 Aug 2010 09-51-35 74D 58.8M 1.2 M Off
    9 Aug 2010 16-16-02 90D 41.2M 1.0 M On
    26 July 2010 15-02-17 120D 46.0M 0.6 M On
    26 July 2010 18-16-50 50D 30.0M 0.6 M Off
    28 July 2010 17-02-15 78D 14.2M 1.0 M Off
    28 July 2010 09-51-00 78D 15.8M 0.4 M On
    17 Aug 2010 10-23-42 83D 58.4M 2.6 M On
    17 Aug 2010 16-01-6 92D 00.9M 1.3 M On

    Re sights on 26 July, looks like the time interval might be to close.

    Let me know what, if anything jumps out at you.

    Thanks.

    Alan
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