New observations from the southern hemisphere have been used to check the periods for the 11 RR Lyrae variables in and around the globular cluster Messier 9. The periods were determined previously with data from northern observatories where M9 can only be observed over a small range in hour angle. Three of the eleven published periods were found to be in error. As a result of this, the mean period of the RRc variables has been revised from 0.279d to 0.341d, the mean period of the RRab variables has been revised from 0.614d to 0.621d,and a star previously believed to be an RR Lyrae has been reclassified as a Population II Cepheid. One of the RRc variables may be a double-mode pulsator. Another variable was studied, but the data were not sufficient for determining its period.

Cone search capability for table J/AJ/89/1707/stars (List of variables)