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    AN5954 bubble octant by Bausch and Lomb
    From: Alexandre Eremenko
    Date: 2012 May 4, 16:53 -0400

    Dear List members,
    Does anyone have this octant or a manual to it?
    I see a picture and a description in Ifland's book.
    Unfortunately this description makes no sense for me:-(
    The main distinction from all other air octants is that
    it is "medianizing" instead of averaging.
    Instead of averaging it takes a median of 15 altitudes,
    with a very simple "medianiser". There is a picture which
    is supposed to show this medianiser in action, and it seems
    clear how it works.
    Let me recall what is the median. You order 15 numbers by their
    magnitude and take the 7-th. This is the median.
    Median has some substantial advantages in comparison with
    the average, if you repeatedly measure the SAME quantity.
    This does not apply however to sextant altitude observatons,
    except for the Polaris and Sun at Noon.
    In general, altitude changes quite quickly and when you take 15 shots,
    the results are very likely to be increasing or desreasing.
    In which case there is evidently no point of taking the median.
    (It will be simply the 7-th shot).
    That's why I am looking for a more reasonable explanation of how this
    sextant really works, or what is it for.

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