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    Re: Direct methods
    From: Dave Walden
    Date: 2007 Nov 2, 14:43 -0700

    Nice catch by George!  Declination can of course be
    less than one degree North or South.  The math works
    for small declination; user interface doesn't.  Quick
    fix:  If declination is less than one degree, enter
    minutes as decimal degrees.
    Revised version is attached which should fix the
    problem more elegantly.
    Has anyone followed the hint in the file name and
    James A. Van Allen, Basic principles of celestial
    navigation, American Journal of Physics -- November
    2004 -- Volume 72, Issue 11, pp. 1418-1424.
    (Google to find online.  Yes, THAT Van Allen!)
    Test data from ICE:
             Celestial Navigation Data for 2007 Mar 20 at
    18 00 00 UT (GMT)
                                  Delta T =  69.5 seconds 
                     For Assumed Location:  Longitude   W 
    77 10.1
                                            Latitude    N 
    38 53.3
                         Almanac Data                   ³ 
      Altitude Corrections
     Object       GHA        Dec         Hc       Zn    ³
    Refr    SD     PA     Sum
                  ø   '      ø   '      ø   '       ø   ³ 
     '      '      '      '
     SUN         88 07.3   s 0 06.0   +49 44.2   197.1  ³ 
    -.9   16.1     .1   15.3
     MOON        67 52.4   n11 51.3   +61 43.8   160.5  ³ 
    -.6   16.9   29.4   45.7
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    File: 103744.vanallenfix_5.xls
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