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    Re: GMT from Lunar Photo
    From: Frank Reed
    Date: 2022 Jan 7, 11:37 -0800

    Antoine, is this star, as highlighted in the Stellarium screen cap below, the star that you were asking about? The J2000 coordinates in Stellarium can usually be trusted without qualification since they are drawn directly from standard sources. The coordinates of date, which are computed by the app, are usually good to some fraction of a second of arc (but maybe not even a tenth of a second), which is good enough for this puzzle. And of course you can take the HIP number and validate the star's location from a variety of astrometric databases online.

    Note that this image counts as "my solution". I estimate that the time of the photo was 01:11:15 UT +/- 15 seconds simply by playing the time back and forth until it looked like the image. I offered that UT up before my original NavList post on this topic on Fred Espenak's Facebook page. He replied with a succint "you nailed it". I didn't ask for further details, like how big is that "nail", because FB astro photos are primarily followed by people in the "ooh and ahh" set who don't want their starry-eyed wonder messed up with any numbers :). And photographers like Fred E are generally in it now for the oohs and ahhs, too. 

    Frank Reed


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