au.parallacticAngle(radec, mjd=None, date=None, observatory='ALMA')Inputs:
CASA <5>: au.parallacticAngle('17:51:00 09:39:00', date='2015-06-21 04:31') MJD= 57194.18819, MJDseconds= 4941577860.0, JD= 2457194.68819 Out[5]: 178.17420355393764-- ToddHunter - 2015-06-19