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    Slide Rule Azimuth
    From: Greg Rudzinski
    Date: 2009 May 29, 12:44 -0700

    An interesting azimuth formula presented by H.H. Shufeldt in his book
    SLIDE RULE FOR THE MARINER (pg. 77)
    
    Azimuth = INV SIN of  COS declination Sin meridian angle  divided by
    COS altitude ( Ho or Hc )
    
    Shufeldt states that Ho or Hc altitudes can be used. The INV SIN
    result  is added or subtracted from 360 or 180 degrees depending on
    orientation.
    
    An alternate arrangement for the formula:
    
    Azimuth = INV SIN of  SEC altitude COS declination SIN meridian angle
    
    I like the expediency of this formula but it does suffer from
    inadequate  slide rule scale resolution for azimuths approaching 270
    or 90 degrees. A trick to by-pass this problem for a sun observation
    would be to directly observe a corrected bearing of the sun (which
    should be low in the sky) for use as an altitude intercept azimuth.
    
    
    
    
    
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