Given the Right ascension in h m s, Declination in deg ' " and the Trigonometric parallax How can I get the cartesian (x,y,z) coordinates of a star? I'm guessing I need 3 separate formulas to get each x, y and z values.
How do I calculate the cartesian coordinates of stars
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trigonometry
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0Why do you need Cartesian coordinates? [In any event...](http://en.wikipedia.org/wiki/Celestial_coordinate_system) – 2010-12-23
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2Then your declination corresponds to $\theta$, right ascension to $\phi$ and parallax to $r$ for a properly referenced spherical coordinate system. See http://en.wikipedia.org/wiki/Spherical_coordinate_system – 2010-12-23
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0@J.M. to plot thing in openGL you need Cartesian coordinates. @Ross - Thanks I'll look into it. – 2010-12-24
1 Answers
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I know this is old, but here is the answer:
http://fmwriters.com/Visionback/Issue14/wbputtingstars.htm
A = (RA_hours * 15) + (RA_minutes * 0.25) + (RA_seconds * 0.004166)
B = ( ABS(Dec_degrees) + (Dec_minutes / 60) + (Dec_seconds / 3600)) * SIGN(Dec_Degrees)
C = distance in light years or parsecs
Cartesian:
X = (C * cos(B)) * cos(A)
Y = (C * cos(B)) * sin(A)
Z = C * sin(B)