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    Re: Milky Way photo navigation challenge
    From: Frank Reed
    Date: 2021 Jun 27, 13:37 -0700


    That's terrific! And yes, I agree on the date: June 13, 2018 based on the position of Saturn. And good call on that being New Moon!

    For the latitude, there's a trade between local time and latitude that will get the base of the Sagittarius "teapot" vertical: later local time, latitude closer to the equator. It works easily at an earlier local time from 20 South or even 25 South. The furthest north I can make it work is about 8 or 10 South at a later local time when the stars in western Libra are still above the horizon (Zubenelhakrabi is visible and not noticeably diminished by extinction). Close enough! Note that the photo itself could have been taken from a latitude much further north and then rotated when it was pasted in. But that's a separate issue. For the sky to look like this, given the orientation as presented, the observer would have to be south of the equator.

    Finally, is it a "day for night"? I wondered about the flags... The grounds are closed at night, so that's a clue, too. I know the 26-year-old "caretaker" at the lighthouse. I pinged him on FB and got a near instant reply back from him earlier this afternoon. He says the flags are "Up and down most days. Overnight once in a while." So, yes, the foreground image is probably a day for night.

    Frank Reed

    PS: The expression "day for night" gets us back to geographic coordinates, too. How you may ask? Well, in a roundabout "Six Degrees to Kevin Bacon" sort of way (Kevin Bacon and Kyra Sedgwick are actually filming in Wickford, Rhode Island this week, just six miles from here, so this has been a topic of conversation). We start with the film trick that you mentioned known as a "day for night" also known as "la nuit américaine" or "the american night" to French film-makers. A famous film by this name was created by famous French film auteur François Truffaut. Truffaut just four years later had a key supporting role as one of the UFO experts in Spielberg's Close Encounters. We could stop there, but Truffaut's character's French interpreter makes an amazing discovery while looking at some numbers being transmitted by the UFO aliens. The numbers are:
    104 44 30,
      40 36 10,
    and the interpreter (played by Bob Balaban) announces that these must be map coordinates! Really? Even when I was 14 (when the movie was released), I thought that was a bit ridiculous. Well, they go with it, and apparently the aliens use the "west positive" and "north positive" standard for coordinate, and also happen to be aware of the location of the Greenwich Prime Meridian and also can translate to sexagesimal coordinates, but they couldn't just come out and spell "Lat Lon" for this one case or even better "Meet us at Devils Tower in the Black Hills"?! Yeah, right. They're super-duper smart so they use latitude and longitude to communicate. Wow... But anyway, there we have it: from "day for night" to "sexagesimal lat lon" in six or fewer steps. I'm gonna call Kevin Bacon right now...

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