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    Re: Formula to determine GHA of Sun?
    From: Samuel L
    Date: 2014 Sep 12, 05:47 -0700

    Bill,

    There's a less complex way to do it if I were so inclined now that I know the facts.

    Backbearing.com has an Sunsight.xls spreadsheet which provides a quick Sun sight reduction. On one its sheets called Calcs there is the entire sequence for determing GHA.  If I were to follow all of the steps in reverse as presented on that sheet then I could figure out how the author of Sunsight.xls calculated GHA. 

    The problem is the amount of time needed to calculate and determine GHA using a calculator- it would be just too long of an equation and way too many steps.

    So, for the moment it's easier to use the Nautical Almanac to get the rough GHA for the UTC hour and then calculate GHA UTC minutes and seconds with a calculator (without going HO 249 Table 3)

    It would be nice to be able to speed up my sight reductions. It now takes around 15 minutes to complete one. That is; from sitting down to drawing the LOP on a UPS. Another BIG problem is that the font size of the Almanac and HO 249. I'll probably go blind, not from the Sun, but from straining my eyes.

    Sam

     

     

     

     

       
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