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    Re: Lunar Distance Puzzle
    From: Dave Walden
    Date: 2011 Aug 19, 18:36 -0700

    It REALLY does work!

    Here's a case generated with Frank's online calculator. (No NOVAS, no JPL) I have no knowledge of what refraction calculation he uses. I pick a time and place and iterate on LD until I get zero error for each of the three stars. I do near and far, then average since I'm dealing with centers at the moment. I use his almanac data. I round the LD's to the nearest 10th of a minute. Seems like a pretty fair test. I get within 20 seconds and 10 nm starting from an hour off in time and 70 miles off in AP. Not bad for the 10th of a minute LD and linear interpolation between hours.


    Nautical Almanac Data for August 16, 2011
    Date and Times are GMT.


    16:00 17:00
    Moon's HP 54.39 54.38
    GHA Aries 204° 42.1' 219° 44.6'
    Greenwich Hour Angle
    and Declination
    The Moon 210° 23' 21"  224° 58' 11" 
    N 3° 1' 42" N 3° 13' 24"
    Fomalhaut 220° 7' 9"  235° 9' 37" LD 33d 23.6m
    S 29° 33' 21" S 29° 33' 21"
    Hamal 172° 44' 14"  187° 46' 42"  LD 41d 58.2m
    N 23° 31' 5" N 23° 31' 5"
    Markab 218° 21' 27"  233° 23' 55"  LD 14d 59.0m
    N 15° 16' 16" N 15° 16' 16"

    (used 50d F, 29.83 in Hg, 0 IC, 0 ht of eye, include both corrections)

    with LD's the the second (which Frank's calc can do):

    time err -4.6s
    lat err .1 nm
    long err 3.1 nm

    for those who are doing it:

    33d 23m 45s

    41d 58m 14s

    14d 59m 1s

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