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    Re: Refraction - Pub. No. 249 and Air Almanac
    From: Marcel Tschudin
    Date: 2005 Aug 27, 15:24 +0300

    We learned here that the refraction tables of Pub. No. 249 and the Air
    Almanac are copies out of the article "The Refraction Table in the Air
    Almanac" by D.H. Sadler in Vol. 5 (1952) of the (then) "Journal of the Royal
    Institute of Navigation".
    For all those, who do not have access to the paper,  here the input data
    which Sadler used for his calculations:
    Standard atmosphere at sea level: Temperature 15degC and pressure
    Lapse rate: -6.5degK/km until 11'000m.
    Refraction coefficient: 1.00028208; it was intended to use a value of
    1.0002718. A footnote explains:
    "The value actually used as the basis of the integrations was 1.00028208,
    corresponding, as far as mu(o) is concerned, to a temperature of 10deg C
    instead of 15deg C. This numerical error, which has been found only in
    checking the manuscript of this paper, will (fortunately) lead to no
    appreciable error in the published table. Values of Ro should be decreased
    by 1 part in 56. Alternatively the table can be corrected by adopting the
    values of Ro unchanged and changing (by a maximum of 5?) the critical values
    of the temperature. In view of the smallness of the corrections, the table
    will be kept unchanged until the more fundamental tables become available."
    I hope that this is of use to all those who try to understand the content of
    this table.

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