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    Re: Willis' Sight Reduction Method
    From: Antoine Couëtte
    Date: 2010 Mar 19, 00:56 -0700

    While we are at "Sight Reduction Tables", and after I tried some of them, if I had to do it again (calculators are SO MUCH easier and nicer with significantly reduced error risk), I would use either one of the following SRT's:

    - the USN HO214 (?) of regular use on board FN vessels. You need to have sufficient room onboard to accomodate their entire set, but they almost always guarantee you a (beloved ...) 0.1' accuracy throughout. However I remember that interpolations for circumpolar stars approaching low culmination in the southern Hemisphere (e.g. Rigil Kent when en route to the Kerguelen Islands) were not quite an easy task, and/or

    - for maximum accuracy throughout, the Admiral Davies's Concise (yes ... definitely "concise" when compared to the HO214 full set) Sight Reduction Tables, but if you are tired, be very careful even if you have a good experience with them (possibilities for errors or inaccuracies from own personal experience), and/or

    - for a number of usual cases (i.e. heights below 70°) the Dieumegard Tables (heights below 70°), and the Bataille Tables for the Azimut, both tables found in the French Standard "Table 900". Both are definitely expeditious with a low risk of error. As regards the Azimut determination, and when in a hurry (sometimes a nice and brilliant expression to upgrade nothing short of a poor excuse for laziness) I would even occasionnally use the Rude Starfinder, once very carefully set (though !) as a function of EACH recorded observation time.

    And, as a last word, I never used Bygraves ... should I purchase one ?

    Best Regards to all


    Antoine M. "Kermit" Couëtte
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