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    Re: Altitude correction using Artificial Horizon?
    From: Chuck Taylor
    Date: 2000 Sep 05, 10:38 PM

    To amplify a little what Dan said:
    You can find the refraction correction under the "Stars and Planets"
    (center) column of page A-2 in the Nautical Almanac.  For parallax, add
    0.1' for 0 to 60 degrees apparent altitude, nothing for higher apparent
    altitudes.  If you superimpose the two images of the sun on your
    artificial horizon, this all you need (unless apparent altitude is less
    than 15 degrees, in which case you need to add in T&B corrections from
    page A-4).  Do not use the "Sun" column of page A-2 for superimposed
    Chuck Taylor
    Dan Allen wrote:
    > Parallax and refraction still need to be applied.  Both of these depend upon
    > the angle observed, while refraction is also a function of temperature and
    > barometric pressure.  These are combined in most sight reduction schemes are
    > are often referred to together as an "altitute correction".
    > Dan Allen
    > -----Original Message-----
    > >> Is it necessary to apply any correction for altitude when reducing a sun
    > >> sight taken with an artificial horizon?
    > Kirk Benson
    > 34d 10.8' N
    > 84d 12.7' W

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