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    Intercept method
    From: Doug Royer
    Date: 2003 Jun 23, 11:26 -0700

    I tried again over the weekend to work the Lunar intercept method as
    explained by Mr. Umland.For the 2nd time in as many attempts the results are
    questionable.Are they questionable because of mechanical errors of the
    sights,errors in reduction methods or errors in the interpretion of the math
    from chapter 7 of Mr. Umland's papers?
    I don't believe it to be errors in the mechanics of the observations.Great
    care was taken to assure accurate observations and equipment.I don't believe
    it to be errors in reduction methods as 3 differant reduction systems were
    used to check the results.The sin-cos method useing a Casio fx-6300
    calculater has the Moon's intercept at 0.5 m A,Mr. Umland's Moon sight
    software has the intercept at 0.3 m A,the Admiralty's reduction software has
    the intercept at 0.4 m A.
    I believe I am not useing the intercept formula properly or it is flawed.I
    got a chrono error of  5.9 sec. slow useing the intercept method.Knowing my
    chrono was not that slow I set up and checked the chrono's error useing
    equal altitudes.The chrono error thus obtained was very close to the actual
    known chrono error.
    Mr. Umland's Moon and Sun reduction software is nice to use and has features
    I've not seen on other software such as getting the intercepts directly from
    the readings from a bubble sextant or artificial horizon.Times are Zd + 7.
    GPS pos. = 32*53.05'N,114*49.90'W
    06-22-03 030311 3 star fix AP = 32*53.2'N,114*49.7'W
    06-22-03 031439 Moon UL Hs=23*13.4',Ho=23*46.8',Hc=23*47.3',I=0.5 m
    A,Zn=106.3*,GHA=53*24.6',LHA=298*34.9',dec=0*10.1'N,v=8.18',d=10.46'.
    f=-0.7348,delta T"=-5.93 sec. Chrono error is 5.9 sec. slow.
    Equal altitudes chrono error
    Antares Hs=58*34.2' at 221444 on 06-21 and 000303 on 06-22. 240303 +
    221444/2 = calculated Antares mer. pas. at 230854.Mer. pas. Antares at
    114*49.90'W = 230853.Chrono is 1 sec. slow.
    Sun LL at Hs=109*51.0' at 100700 and 151536 on 06-22. 100700 + 151536/2 =
    calculated Sun mer. pas. at 124118.Mer. pas. Sun at 114*49.9'W =
    124117.Chrono is again 1 sec. slow.
    What am I not seeing or doing correctly with the Mr. Umland's Lunar
    intercept method?
    
    
    

       
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