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    Non-adjustable sextant error calibrations
    From: Doug Royer
    Date: 2004 Feb 2, 14:57 -0800

    After reading Joel's post I started to think about this matter.Frank started
    a thread(part 1 of 2) on measuring the angles between stars to find error.I
    was interested in the subject but didn't persue it further untill part 2 is
    written.However,after Joel's post I wonder if one can calibrate the
    instruments' non-adjustable error useing this or some other method.
    Doesn't collumation error have to do with the alignment of the scope to the
    frame?I've read in some book also,that to check collumation one places a
    grid a certain distance from the sextant and scope and checks for the error
    in that way.I'll have to dig around in these books to find if that is what
    was being written about.
    I've read in older nav. books a procedure called "interstellar angles" or
    some such.There was even a table with angles between stars(such as Sirius to
    Spica,Spica to Aldebahran etc.)that spanded close to long angles to measure.
    My question is : is this the method one can use to find or calibrate the
    non-adjustable error that Fred states?
    As I posted awhile ago I took my sextant into Baker Marine years ago(when
    they offered this service)to have the arc error checked(for a healthy
    sum)only to find out it was well in spec < 10" of arc over the entire arc of
    130*.So,because of the cost of this couldn't Fred or any of us use this or
    some technique to find the error in some of the older sextants that state
    the error on the certification papers inside the sextants' box?

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