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    Re: Angular Distance Between Stars By Camera and Sextant
    From: Brad Morris
    Date: 2012 Sep 18, 13:44 -0700

    J2009.5 (Epoch July 2009)  The data presented are for July 2009. 

    I could always get the latest  Astronomical Almanac (not Nautical Almanac, which clearly suffers) from the U S Naval Observatory.  The data will then be current.

    The question was more of the suitability of the # of digits of the data, rather than the data for 2009.   A tenth of a second RA and a second of declination.

    Best Regards

    On Sep 18, 2012 4:34 PM, "Marcel Tschudin" <marcel.e.tschudin@gmail.com> wrote:
    Brad, regarding your question

    On Tue, Sep 18, 2012 at 9:57 PM, Brad Morris <bradley.r.morris@gmail.com> wrote:


    The USNO issues "The Astronomical Almanac"  US Gov't Printing Office.  My last copy was from 2009.

    Alkaid (Bayer 85 Eta Ursae Majoris SAO 44752 HIP 67301) in that 2009 Astromonical Almanac as RA 13 hours 47 minutes 54.9 seconds Declination +49 degrees 15 minutes 58 seconds.

    Alioth (Bayer 77 Epsilon Ursae Majoris SAO 28553 HIP 62956) in that 2009 Astronomical Almanac as RA 12 hours 54 minutes 26.7 seconds Declination +55 degrees 54 minutes 30 seconds.

    You estimated that we would need data to 1/100 moa (minute of arc) in order to properly calibrate the arc.  Do these values meet your criteria?

    I guess that these published values correspond to some epoch data. Before they could be used for the purpose discussed here they have to be converted to the date, time and location of the observation. It is these converted results which would preferably be shown to 1/100th moa for calibrating to a few seconds of arc. In a program like e.g. the one from Andrés the calculations are done with more significant decimals and are therefore expected to be sufficiently accurate for your purpose. The problem with table values, like USNO's Almanac data, are the limited number of decimals shown from the computed values which likely also had a higher accuracy.

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