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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.

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    Why do you need Cartesian coordinates? [In any event...](http://en.wikipedia.org/wiki/Celestial_coordinate_system)2010-12-23
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    Then 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_system2010-12-23
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    @J.M. to plot thing in openGL you need Cartesian coordinates. @Ross - Thanks I'll look into it.2010-12-24

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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)