... Alfa_ang is a GUI for the rotang routine. The purpose of this routine is to calculate the optimum rotation angle for ALFA given the RA and Dec of a source and the date and time of the observation. The routine also returns the azimuth and zenith angle of the telescope at the requested time, thus it can be used to find the correct rotation angle and azimuth for the Fixed Azimuth Drift Scan observing mode used by the AGES drift precursor observation. ... To run alfa_ang at Arecibo: . ...