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    Re: Modifications to 2102-D
    From: Gary LaPook
    Date: 2009 Apr 18, 16:52 -0700

    I might have one of those at home, I will look when I get back from
    Europe.
    
    gl
    
    On Apr 19, 1:16�am,  wrote:
    > Hi Gary
    >
    > That was quite interesting. �The 2102D can be quite a useful tool. �I 
    perform observations on a south facing beach in the northern hemisphere and 
    have played endlessly with the tool. �
    >
    > I just use my to determine which stars would be practical. �Since my 
    latitude is 40 north, it places me right between the N35 and the N45 blue 
    templates. �Therefore, the altitudes and azimuths given really don't do the 
    trick. �
    >
    > I first plot the four navigational planets, the sun and the moon via the red 
    template. �Then I use the blue N45 to pick out those bodies which will fall 
    in the section of the sky that is useful to me. �Unfortunately, this is only 
    about 135 degrees, so it kind of limits my choices.
    >
    > Once I have the list, I swap over to the Bygrave to calculate the altitude 
    and azimuth of each. �That way, when I am ready to swing the arc, I can 
    preset the sextant to the expected altitude and point via the compass. 
    Generally, the star is right in the telescope!
    >
    > My motivation for the 2102E was the lack of a template for my latitude. �Gee 
    whiz, I thought, how hard could it be to make one? �If you have looked into 
    the excel spreadsheet in any detail, you will note it isn't exactly easy! 
    �And if I wanted deadly accurate blue templates, it would be enormously 
    computationally expensive. �I would extend the number of points to smooth out 
    all of the straight line, but when I tried this approach, the display was all 
    herky jerky. �For making a static template, though, that would be the 
    recommended approach.
    >
    > From other postings in the archives, I get the sense that you really enjoy 
    these non-electronic means of solution. �So do I! �Have you encountered the 
    "Dunlap Sunrise Sunset Computer" in your travels? �A picture of it is in my 
    copy of Dutton's. �Looks like an interesting solution to a non-trivial 
    problem.
    >
    > Best Regards
    > Brad
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