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    Re: Time of planet rising - formula
    From: Bill Noyce
    Date: 2001 Dec 10, 8:48 AM

    > How can I determine what time a planet will rise?
    
    A simple formula will give the LHA at which a body's
    computed altitude (Hc) is zero, given the body's
    declination and your latitude:
    
    cos(LHA) = tan(dec)*tan(Lat)
    
    This ignores refraction and dip (height of eye).
    Refraction at the horizon is about 34', but somewhat
    variable; the planet will actually appear to rise or
    set when its Hc is about 34' below the horizon.  Unless
    your atitude is very high, you can approximate the
    actual rise/set time by adding refraction and dip to
    the LHA.  Then apply that angle (east for rising, west
    for setting) to your longitude to get GHA, and use the
    almanac to find the time at which that GHA occurs.
    

       
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