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    Re: AN5954 bubble octant by Bausch and Lomb
    From: Alexandre Eremenko
    Date: 2012 May 8, 19:52 -0400

    Gary,
    
    Let's take the second series, for example:
    (I reformatted to make it readable)
    
    >> 23:48:18  34d 51'
    >> 23:48:31  34d 48'
    >> 23:48:46  34d 47'
    >> 23:49:04  34d 41'
    >> 23:49:21  34d 39'
    >> 23:49:37  34d 33'
    >> 23:49:51  34d 33'
    >> 23:50:09  34d 27'
    >> 23:50:21  34d 25'
    
    The median time is 23:49:21, the median altitude is 34d39'.
    So taking the median just rejects all observations except the
    9-th one. So what is the point to bother with 9 observations
    and reject 8?
    
    The medianizing aircraft sextant actually takes the AVERAGE time
    and median altitude. In this example, we obtain time 23:49:19,
    and the same altitude.
    
    What did we gain? Nothing.
    
    Now let me repeat what I claimed: if you shoot accurately enough so that
    your altitude changes monotonically, or almost monotonically,
    taking median is the same as taking the middle observation and rejecting
    the rest. Then why bother shooting several times?
    The median is not better than one shot.
    
    It only makes sense when your single shot accuracy is bad,
    worse than the change of the altitude between the shots,
    as it happens in your first series, which is not monotone.
    
    Alex.
    
    
    
    

       
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