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    Refraction correction
    From: Peter Hakel
    Date: 2009 Apr 13, 11:06 -0700
    Dear NavList members,

    The HO 249 (intended for air navigation) tables include the "standard dome refraction" table for additional correction affecting the sextant reading.  I am wondering, if the sun or the moon are observed through a cloud layer that is thin enough so that the disk is still visible, what is the additional atmospheric refraction effect on the sextant altitude?  Can the experts on this list point me to any discussions on the subject or is this a non-issue? If this does make a practical difference, one might have to consider the effective thickness of the cloud, its composition (liquid droplets vs. ice crystals), color dispersion, etc...

    Thank you.

    ======================================
    Peter Hakel
    http://www.navigation-spreadsheets.com/

    Spreadsheet demos using an iPod Touch:
    http://www.youtube.com/watch?v=usFK4As6_hE
    http://www.youtube.com/watch?v=h8hwHv1hTpc
    ======================================




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