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    Re: Polaris in daytime
    From: Lu Abel
    Date: 2012 Jan 25, 10:03 -0800
    One thing not discussed that would affect the visibility of any star during daylight is the amount of atmospheric moisture.  Moisture scatters the sunlight and so would obscure one's ability to see a star, even if bright and away from the sun. 

    I'd feel much more confident about being able to see a star during daylight if I were in the desert than if I were in the jungle.   I have not experienced it myself, but have heard reports of people being able to see stars during the daytime when they're in a narrow slit canyon in the deserts of the southwestern USA.   They also report that the sky above the slit appears black, not blue.


    From: Geoffrey Kolbe <geoffreykolbe@compuserve.com>
    To: NavList@fer3.com
    Sent: Wednesday, January 25, 2012 6:31 AM
    Subject: [NavList] Polaris in daytime

    Surveyors often need to find true North to lay out the initial reference line off which a building is measured. These days, with GPS gizmos, there is no difficulty in this. But pre-GPS, true North was found by taking a timed azimuth measurement of the sun, or of Polaris which, the text books say, is visible during the day using the average theodolite 30x scope.

    When I was in Egypt a few years ago doing an experiment on pyramid alignment, I tried to find Polaris using my theodolite. I had taken azimuth measurements off the sun, so I knew where to look, but I never saw nothing. Polaris is too high in these latitudes (Scotland) to see with a theodolite, so I am not able to try here.

    Has anyone in lower latitudes managed to see Polaris in the daytime through their sextant telescope, or through any other telescope? I was wondering how big a telescope you need to see Polaris in the daytime.

    Thanks

    Geoffrey Kolbe






       
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