The globular cluster Palomar 13

The B and V magnitudes of 122 stars in the globular cluster Palomar (Pal) 13 have been determined through examination of plates from the 200-inch Hale telescope. The new data extend the preliminary estimates of Ciatti et al. (1965) of the color-magnitude diagram and luminosity function of Pal 13 to the upper main-sequence. The main sequence turnoff for B-V was at 0.38 + or - 0.03 mag, and at 21.1 + or - 0.2 mag for V. The luminosity function for Pal 13 was found to be similar to that of M3 over a central radius of 8 arcmin, when it was reduced by a factor of about 60. Integration of the luminosity function yielded an apparent magnitude of V = 13.75. The integrated absolute magnitude of the cluster was Mv = 3.4. Assuming a mass/luminosity ratio of 1.6, a mass of about 3 x 10 to the 3rd solar mass is estimated.