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    Re: Longitude by Sunset
    From: Marcel Tschudin
    Date: 2012 May 6, 11:44 +0300

    You wrote:

    My main source is the article "Refraction near the horizon" by
    B. Schaeffer and W. Liller, Publ. Astr. Soc. of the Pacific, 102(1990)796-805.
    The authors and their friends made massive observations trying to time
    sunsets with their watches. The conclusions are discouraging.

    This publication has to be used with caution for at least two reasons:
    (1) The various observations are provided without any information on atmospheric conditions (temperature and pressure).
    (2) When I tried to use these data about 5 years ago I found that the coordinates provided by Liller were wrong. He provided me then the correct ones by private communication.

    Do here is a little research project for an interested List member who
    has a luxury of having a sea horizon facing West.
    Time a Sunset and Moonset on the same day, as well as you can
    and do it for several days...

    In some NavList contributions during February 2010 on "Seeing Moon rising an setting ?" I questioned whether it would generally be possible to see the moon actually setting (or rising). The extinction of the atmosphere close to the horizon was at least during my (few) observations too strong.

    I would be interested in the results of this project. Unfortunately I can not contribute anymore because I live presently not close to the sea.


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