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    Lunar Occultations - help needed please
    From: Geoffrey Kolbe
    Date: 2015 Oct 1, 18:08 +0100


    On Sat, Sep 26, 2015 at 2:42 PM, Bob Crawley  wrote:

    Thanks for that Geoffrey - I've used your method to try and replicate the prediction for Aldebaran on 29Oct2015 at the Orwell Observatory near me in Suffolk (oasi.org.uk). I get close with 215130 immersion 215900 emersion compared to their prediction of 214949 and 224824UT. It became easier when I remembered that I could get all this calculated for me on the usno site. 

    ​It should be remembered that the Moon's celestial longitude is changing at a rate of about half a minute of angle in one minute of time. This is the angular rate at which the Moon will be advancing on Aldebaran. 

    The program on the USNO site is similar to most sight reduction programs in that while it calculates altitude to the nearest tenth of a minute, it only calculates azimuth to the nearest tenth of a degree. When plotting the change in azimuth vs the change in altitude, I would suggest you need much better precision than this. I would suggest you take the calculated altitudes for Moon and star from the program and use these to calculate the azimuths using a scientific calculator to get a precision for azimuths similar to the calculated altitude. 
     
    ​Geoffrey Kolbe​


       
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