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    Re: Latitude 48 Article Image as CN Piloting Exercise
    From: Frank Reed
    Date: 2020 Aug 23, 09:45 -0700

    Greg, you wrote:
    "David suspected that this image was a morning twilight capture on 16 August 2020 in the general area of Smith Island (48.3° north 122.8° west). The caption under the photo refers to sunset."

    Well, it only refers to sunsets, and it does so rather indirectly. Of course, given the dates in question, it can only be pre-dawn. And probably no more than 15 minutes before dawn (since Pollux is not visible at all) and also probably not less than 5 minutes before dawn. 

    "I am in agreement with David on this and have performed a CN piloting exercise using the moon azimuth and a moon diameter as angular reference."

    Why not use the Moon-Venus angle (lunar distance) as your angular reference? You know the date, the approximate local time and the approximate longitude. Load that up in your favorite simulation software, and you'll have some reasonable, relatively narrow ranges on that angle. 

    Frank Reed

    PS: Thos NGA javascript apps that you use should carry a disclaimer! Be careful...

       
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