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    Re: equinox
    From: Jay Borseth
    Date: 2004 Mar 21, 16:26 -0800

    I am not an astronomer (IANAA), but I would guess the discrepancy lies in
    the assumed values of deltaT, the difference between Dynamical Time and
    Universal Time.  For a taste of the topic, see:
    
    http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=DWELLS.9
    5Mar19183528%40fits.cv.nrao.edu&rnum=8&prev=/groups%3Fq%3Dusno%2Bdeltat%26hl
    %3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26selm%3DDWELLS.95Mar19183528%2540fi
    ts.cv.nrao.edu%26rnum%3D8
    
    I recently changed the values of deltaT used by Pocket Stars
    (http://www.nomadelectronics.com) to more closely match USNO values:
    
    // julian                         deltaT
    2451544.5000000, /*2000.0000,*/   63.83,
    2453371.5000000, /*2005.0000,*/   66.00,
    2455197.5000000, /*2010.0000,*/   70.00,
    
    Using these values for deltaT, Novas, and DE405, the equinox as calculated
    by Pocket Stars was at 6:48:53.
    
    - Jay
    
    
    -----Original Message-----
    From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]
    On Behalf Of Fred Hebard
    Sent: Sunday, March 21, 2004 4:05 PM
    To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
    Subject: Re: equinox
    
    Here are the Sun's declination as reported in the Nautical Almanac
    versus time.  Looks pretty linear to me.  The discrepancy may lie
    elsewhere, such as the system of coordinates.
    
    When I said the time was exactly 6:48:00, I meant the calculation
    indicated 6:48:00, not 6:48:01 or 6:47:59.
    
    As both you and I said, it would be nice if an experienced astronomer
    would chime in here.
    
    Fred
    
    
    

       
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