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    Re: Difference between HO 249 and USNO website
    From: John Almberg
    Date: 2016 May 17, 11:27 -0700

    Hi Gary,

    Thanks for your answer. I guess there is a delay between when a message is posted and it appears on the website, because I figured it out myself before your answer appeared. 

    It all makes sense now, except for the refraction correction. Am I correct in thinking that I can use the A2 Altitude Correction table for "Stars and Planets" to find a rough estimate of the refraction + paralex correction? 

    For example, if I look up the correction for Ha of 21 30', I get -2.4, which is the correct value. 

    It also seems logical that the correction for a point would be the same as for the middle of the Sun. 

    Thanks for your input. 

       
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