Function raFK5toFK4radians( raFK5, decFK5 )

Description:
Converts a J2000.0 FK5 position to B1950.0 FK4 at an epoch of B1950.0 yielding Declination. This assumes zero proper motion, parallax and radial velocity in the FK5 frame.
Parameters:
raFK5 (floating point)
right ascension in J2000.0 FK5 system (radians)
decFK5 (floating point)
declination in J2000.0 FK5 system (radians)
Return Value (floating point):
right ascension in the FK4 system (radians)
Signature:
double raFK5toFK4radians(double, double)