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    Re: GMT from Lunar Photo
    From: Bill Ritchie
    Date: 2022 Jan 8, 13:29 -0800

    Thank you, Peter, for identifying the occulting star as HD 202635. I fed its Simbad J2000 coordinates and proper motions to Astron's custom star utility and 'adjusted' the time to achieve a near limb sextant arc of zero. My result for the time of occultation was 01:11:47 for an altitude of 1450m.

    I then looked at the adjacent star near 12 o'clock and one fifth of a Moon radius from the limb (HD 202672). It is an optical double and Fred's wonderful image shows the companion faintly. Pixel scaling gave a distance of 2.84' from the near limb and a time of 01:11:40. I used the near (shutter closing) end of the (30 second exposure?) star trace.

    The screenshot attached is of the first result. I would put more weight on that as it does not involve scaling.

    Sorry to be a late entrant for this quiz - I am in the middle of changing my Moon calculation method from using Jan Meeus' 60 most significant terms of the ELP-2000/82 theory to the 577 most significant terms of the ELP/MPP02 lunar laser radar theory. I used the latter for the above results, which are about four seconds earlier than those given by the present release version. 

    Antoine, s'il vous plaît voir ceci HD 202635 et cela HD 202672 pour les détails que vous recherchez.

    Bill Ritchie

    50N 003W


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