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    Re: Star-star distances for arc error
    From: Frank Reed
    Date: 2009 Jun 19, 23:07 -0700

    Peter, you wrote:
    "Yes, that's the one.  My edition says:
    R = 0.0167 / tan( H + 7.32/(H+4.32))"
    
    Yeah, that would explain it then. That formula is an empirical fit to the 
    refraction table. It's close enough for most navigational calculations. That 
    particular formula (an earlier variant of it) was originally published in the 
    1980s, I think, by George Bennett. Back then when computing devices had very 
    limited memory and slow processors, this was a great thing: a nice compact 
    equation for refraction at any altitude. But these days??
    
    -FER
    
    
    
    
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