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    Re: Position from a photo
    From: Robert Bernecky
    Date: 2013 Jan 7, 15:27 -0800

    This is more food for thought than an answer to your question.

    My first thought is that it is implausible that a person would try to encrypt location information in a photograph. It would be easier to encrypt the information in the description written on the back of the picture.

    Instead, let’s imagine the discoverer unintentionally divulges location information by means of his photographs. One scenario: the location has a deep jewel-encrusted shaft purposely built so that on special days the sun shines directly down it, to illuminate a golden parabolic mirror (why not?). The explorer takes a photograph looking down into well at the exact time the sun is shining directly overhead as proof of his find. Later that day he is struck by the sight of three planets, Mercury, Venus and Jupiter sitting just above the horizon at sunset. He takes a photograph and remarks that Jupiter and Venus appear almost as one body.

    After Mercury fades beneath the sands, he notices that the full moon, glowing red, is rising in the east. The moonlight lends a different, mysterious look to his surroundings, and he takes a number of photographs of the site, the moon and the sky in the background.

    If we put the location at N 17º 49.7’ E 29º , then on 1941 May 11 10:00:17 GMT the sun will be at Ho 90º. At 16:50:00 GMT Venus and Jupiter are close to conjunction and dipping below the horizon. Mercury sits a little above the pair. Stellarium can show the scenario. This should set the date, from which we get the sun’s declination and thus latitude. Our real hope is that a computer can match the star field behind the moon to narrow the estimate of GMT to a few minutes. At some point the explorer must tell us that this photograph of the moon was taken exactly xx hours and minutes from the time the sun stood overhead. It’s not obvious why he would mention this. Perhaps he is believes in numerology or astrology and the time difference strikes him as significant. In addition, we must assume he is a bit naive about disclosing this information.

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