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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def ConvertRADecToThetaPhi(RA, Dec, GPSTime):
 """ ConvertRADecToThetaPhi - function to convert right ascension and declination of an astronomical source to theta and phi in the geocentric coordinate system. RA - Right ascension of source. Dec - Declination of source. GPSTime - GPS time that the GW signal from the source reached the 		 geocenter. Returns Theta - Polar angle of source's sky position in geocentric coordinates. Phi - Azimuthal angle of source's sky position in geocentric coordinates. Sarah Gossan 2012. """
 
                
    # Get Greenwich mean sidereal time corresponding to GPSTime 
    GMST = ComputeGMST(GPSTime) 
            
    # RA -> Phi
    Phi = RA - GMST
            
    # Dec -> Theta
    Theta = np.pi/2. - Dec
            
    return Theta,Phi