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    Re: Basics of computing sunrise/sunset
    From: Greg Rudzinski
    Date: 2009 Jun 17, 16:41 -0700

    Even though the altitude is negative enter it into the formula as
    positive. Add the second part of the formula if latitude and
    declination are the same name(north or south) and subtract if
    contrary. Be sure to apply the equation of time in the correct
    direction and the same goes for the arc to time correction for the
    angular difference between the longitude of the observed sunset and
    the time zone meridian. If sunset is before 1800 LMT add 180� to the
    formula angle. If sunset is after 1800 LMT subtract the formula angle
    from 360�. Dip is also a factor to corrected for.
    On Jun 17, 1:41�pm, "Christian Scheele"  wrote:
    > I'm trying to solve the following sunrise/sunset astronomical triangle and
    > am encountering unexpected pitfalls.
    > cos(LHA) = [sin (a) - sin (lat) sin(dec)]/ cos(lat)cos(dec)
    > where I am assuming a = -0.83 degrees
    > It is of course something very basic and I'm almost embarassed to say that
    > although I keep rechecking what I'm doing, I remain with an error of about
    > 15 minutes by the time I get to the final result in mean zone time. Before I
    > drag everybody into it, could somebody please tell me whether there are any
    > snags that I should look out for?
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