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    Re: Eclipse Lunar
    From: Paul Hirose
    Date: 2017 Aug 22, 13:14 -0700

    On 2017-08-21 12:48, Greg Rudzinski wrote:
    > The moment of extinction of the 21 August 2017 eclipse is captured by a 
    Canon Rebel DSLR with 200mm Super Takumar Pentax lens. The lunar distance is 
    almost zero as seen in the image (about 0.3' to go by pixel measure).
    
    The picture appears to be almost the end of the eclipse. In the
    screenshots the observer data are N34 10.5, W119 13.8, +7 ft height eye,
    75 F, 29.98 inches Hg, 18:41:29 GMT. (Temperature and pressure have no
    effect on lunar distance if the limbs are practically in contact.)
    
    With the JPL HORIZONS online calculator I get:
    
      Date__(UT)__HR:MN:SC.fff     Azi_(a-appr)_Elev Ang-diam
      2017-Aug-21 18:41:29.000 *m  136.6403  61.4166 1897.471 (Sun)
      2017-Aug-21 18:41:29.000 *m  135.7496  61.1050 1955.369 (Moon)
    
    The "UT" time in this case is UTC. Elevation is the airless
    (unrefracted) angle. Angular diameter is arc seconds. The "*m" means
    it's daytime and the Moon is above the horizon.
    
    I calculate center to center distance = .5296°. After subtracting
    semidiameters and converting to arc minutes, I get lunar distance =
    -0.33, i.e., the Moon is inside the Sun's limb.
    
    It's much easier to use the Lunar4 program, which does all that
    automatically and also says -0.33.
    
    

       
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