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    Re: What do stars look like in your eye?
    From: Joel Jacobs
    Date: 2004 Apr 24, 09:27 -0400

    Hi Jim,
    
    Its been some time that I've done any star sights. So this is from memory.
    
    Stars always appeared to me just as a point of light and flickered, as in
    "flicker, flicker little star". Since, as you said, they are just a
    pin-point of light, flickering aside, I would forget the extraneous, and
    just used the spot that I visualized as the pin-point, and place it on the
    horizon.
    
    The planets on the other hand always appeared to me as a much brighter beam
    of bright light. I much preferred using them because of my eyesight. Venus,
    the brightest, was my favorite because of its intensity, and because it is
    tied to the Sun and rises in the morning and sets in the evening just about
    where the sun will rise and or has just set.
    
    Your index error under normal conditions should not be changing. I didn't
    find it necessary to check more than once or twice to see that it was the
    same. I don't understand your meaning of "screw the index image down to the
    horizon image". Unless to us Yanks, that means bring the image down to the
    horizon?
    
    Joel Jacobs
    
    
    ----- Original Message -----
    From: "Jim Thompson" 
    To: 
    Sent: Saturday, April 24, 2004 7:55 AM
    Subject: What do stars look like in your eye?
    
    
    > I wonder where my right eye's biological optics stand compared to
    > experienced sextant-users.
    >
    > Stars appear to me in my sextant telescope as very slightly fuzzy
    pinpoints
    > of light with a few sharp radiating lines projecting out of them.  The
    > effect is less with higher magnification, but still there.  This makes
    > finding dead center of the star image a little difficult for me.  What do
    > you see?
    >
    > Venus last night was simply a bigger star-like image.  Frank Reed
    suggested
    > putting the center of Venus on the moon's limb and accounting for SD, but
    > there is no way that I could see that with my biological and physical
    > optics.  Is that average or bad?
    >
    > Even with my 6x40 telescope, measuring index error on a fainter star resul
    ts
    > in an imprecision of +/- 0.1-0.3' on successive readings, in part because
    I
    > cannot precisely see where the centers of the two images exactly coincide.
    > I usually take about a dozen readings for IE, and always screw the index
    > image down to the horizon image.
    >
    > Jim Thompson
    > jim2{at}jimthompson.net
    > www.jimthompson.net
    > Outgoing mail scanned by Norton Antivirus
    > -----------------------------------------
    
    
    

       
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