How do I calculate the cartesian coordinates of stars 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.

I know this is old, but here is the answer:

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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)