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    Re: Moonrise-over-Connecticut
    From: Paul Hirose
    Date: 2021 Nov 6, 14:28 -0700

    On 2021-11-05 14:30, Peter Blaskett wrote:
    >           Celestial Navigation Data for 2021 Nov  6 at 11 43 35 UT (GMT)
    >                                Delta T =  87.7 seconds
    >                   For Assumed Location:  Longitude       0 00.0
    >                                          Latitude        0 00.0
    
    At that time and place, with the ICE delta T, the Lunar 4.4 program gives:
    
    Moon geocentric apparent place
    244°53.26' -21°54.44' equinox RA, dec
    135°43.80' +58°35.81' geocentric az, el
    
    However, the correct delta T is 32.184 (a fixed value) + 37 (until the
    next leap second) - -0.107 (UT1-UTC from IERS Bulletin A). The sum is
    69.29 s. With the correct delta T:
    
    244°53.06' -21°54.39' equinox RA, dec
    135°43.97' +58°35.99' geocentric az, el
    
    ICE altitude error is almost 0.2'. Since the ICE delta T is 18.41 s too
    large, the position of the Moon in its orbit is correct if we move UT1
    back that much. But now Earth rotation has not carried the observer far
    enough east. The solution is to convert the time correction to arc and
    move the observer east. Result with the wrong delta T but corrected UT1
    and observer longitude is practically perfect:
    
    244°53.06' -21°54.39' equinox RA, dec
    135°43.95' +58°35.98' geocentric az, el
    
    --
    Paul Hirose
    http://sofajpl.com/
    

       
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