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    Re: Sight Reduction Tables (HO 249 Vol 1 and HO 229 Vol4) - AProblem
    From: Jeremy C
    Date: 2015 Nov 22, 14:00 -0800

    The best way to use HO249 Vol1 is to first use it to pre-select your stars and get approximate altitudes and azimuths.  Once you have those on your "cheat sheet" you go out and shoot those bodies and reduce them using the tables.  Once plotted you apply the fix correction and you are done.  You can even pre-calculate the corrections as you already know the approximate altitude of the stars along with IC and DIP, and usually you can pre-insert the hourly GHA of Ares and the SHA of the stars.  These were the tricks shown to me by an old ship's master who could have a fix on the chart faster than I could shoot a round of stars.  He was "cheating" by doing most of the math prior to shooting.  All he really did was look up the GHA increments for the exact time he took each sight and run the rest of his form.

    If you go "off the reservation" for star selection, you will have to use an alternative volume or reduction method. For a star night, I will shoot as many of the 249 stars as I can shoot along with a few planets and/or the moon if available.  Sometimes I will shoot a known, bright star, e.g. Hadar, Sirius, Canopus, even if they are not one of the selected stars and do a 229 or computer reduction.

    JCA

       
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