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    Re: Polaris in daytime
    From: Geoffrey Kolbe
    Date: 2012 Jan 25, 16:44 +0000

    Hello Greg
    
    Yes, its photons that counts. If Sirius is 23 times as bright then I
    need an object lens that is about 4.7 times the diameter of yours.
    (4.7 is the square root of 23)
    
    So, can you tell me how big your object lens is?
    
    Thanks
    
    Geoffrey
    
    At 14:59 25/01/2012, you wrote:
    
    >Geoffrey,
    >
    >I have been able to observe daytime Sirius using a 4 power sextant
    >scope. Since Sirius is 23 times as bright as Polaris then a 92 power
    >scope should do the trick.
    >
    >Greg Rudzinski
    >
    >
    >[NavList] Polaris in daytime
    >From: Geoffrey Kolbe
    >Date: 25 Jan 2012 14:31
    >
    >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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