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  1. #1

    Default How can I get Sun altitude in the Java Script?

    Hi!
    I am creating my own script for taking dark frames. I need to be sure the shooting is at dusk. How can I get the altitude of the sun in a java script? Or perhaps there are other ways to determine that the shooting o is at dusk?

  2. #2
    Join Date
    Oct 2005
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    Mesa, AZ
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    Assuming you have the ASCOM NOVAS COM Positional Astronomy engine, and Kepler Orbit Engine installed (API Docs Included), this should work for you, given the current full Julian Date "JD":

    Code:
    var KT = new ActiveXObject("Kepler.Ephemeris");
    KT.BodyType = 0;                                            // Planet
    KT.Number = 3;                                              // EARTH
    var KA = KT.GetPositionAndVelocity(JD);
    var tvec = new ActiveXObject("NOVAS.PositionVector")
    tvec.x = -KA(0)                                             // Reverse Cartesian vector for Sun from Earth
    tvec.y = -KA(1)
    tvec.z = -KA(2)
    var RA = tvec.RightAscension                                // J2000 Equatorial, convert to alt-az
    var Dec = tvec.Declination
    If you have ACP available you can use its CoordinateTransform to go from RA/Dec to Alt/Az.
    -- Bob

  3. #3

    Default

    Thank you Bob! It works!

  4. #4
    Join Date
    Oct 2005
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    You're welcome :-) :-)
    -- Bob

 

 

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