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:
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
X = (C * cos(B)) * cos(A)
Y = (C * cos(B)) * sin(A)
Z = C * sin(B)