Periods for nineteen RR Lyrae variables in NGC 1851

Periods, light curves, mean B magnitudes, and positions are presented for 12 previously known and seven recently discovered RR Lyrae variables in the southern globular cluster NGC 1851. From the periods and shapes of the light curves, it is concluded that five of these stars are type RRc variables, while the remaining 14 are of type RRab. The mean magnitudes of all but two of the variables are found to be very similar to one another, which implies probable cluster membership. A distance modulus of 15.3 mag is obtained for NGC 1851, and the mean period of the RRab variables is determined to be 0.573 day, indicating an Oosterhoff type I system. The ratio of the number of RRc to RRab variables is shown to equal 0.36, which suggests that NGC 1851 remains in approximately the same position relative to the other Oosterhoff type I systems.