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    Re: BS XM DS Daytime Venus, Redux
    From: Jeremy C
    Date: 2011 Jan 20, 07:08 EST
    Greg,
     
     
    I reviewed the information that Henry provided as well as my numbers and I think that I am perhaps taking a different path to the same place with the back sight math.  I also checked my hand logs and find Hs to be 101-35.1.  I agree that diagrams are very helpful to try and figure this stuff out.
     
    We are lucky here because the observation is a planet so we don't have to worry about semi-diameter unlike the sun.  All of my other backsights have been either of the sun or moon and I seem to remember always observing the true lower limb (it appeared to be an upper limb in the scope) to minimize the complexity of the reduction.
     
    I made this "form" from the Bowditch 1984 article.
     
    In this case, I will run down my methods so that we can compare notes:
     
    -IC   +0.8  (IE is 0.8' on the arc as usual)
    -Dip +9.6
    -------------
    Corr     +10.4
    Hsc 78 - 24.9   (180d - 101d 35.1') complement of the sextant reading
    --------------------
    Hs 78d 35.3'
    Body     -0.2'
    Body'     0.0'  (body is too high and therefore outside of the range of the 2nd correction)
    -------------------
    Hs 78d 35.1'
     
    Zd = 11d 24.9'
     
    Dec = S18d 41.1' (Dec and Lat same name, body closer to pole than position)
    -ZD       11d 24.9'
    ----------------------------
    Lat        07d 16.2' S
       
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