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    Re: Stellarium, refraction, HP
    From: Jim Rives
    Date: 2020 Jan 11, 10:08 -0800

    Hi Ed, 

    I am trying to follow a procedure Frank published under the title "Lunars are Easy"  (now I get the humor!)   The thing I keep running into is using Stellarium's altitudes vs just taking altitudes in the real world.  The almanac needs to know whether the bodies were shot using the upper or the lower limb of the moon and the sun.  Stellarium's altitudes are mid-body.  So, when I try and come up with the refraction correction from the almanac, should I just take the average correction for upper and lower cases?  That seems to be the reasonable thing to do.  BTW, temp that day was 50F and it was a fine clear day but didn't note the barometric pressure.  

    2.0' IE... I guess that's the limit of what's considered acceptable.  Perhaps I'll get brave and get out the little wrench... just hoping I don't make it worse.  Been a steady 2.0' IE for several years so.... 

    Thanks for the feedback.  If I ever get to the end of this clearing I'll share the results.  With so many sines, cosines etc. floating around on the page it seems necessary to go slow and careful.  Once I prove I can do it manually once I'll probably never do it again...except with one of the other methods.  

    I wonder if anyone in the past 300 years has published a derivation of all of these celestial navigation formulae?  


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