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    Re: Modifications to 2102-D
    From: Brad Morris
    Date: 2009 Apr 18, 16:16 -0700

    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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