BVI Photometry and the Red Giant Branch Luminosity Function of M15
We present new BVI photometry containing 40,000 stars of the Galactic globular cluster M15 (NGC 7078) covering a 25×25 arcminute area centered on the cluster with a magnitude range from the tip of the Red Giant Branch to three magnitudes below the main sequence turn-off. Using α -enhanced Dartmouth Stellar Evolution Program models, we find an age of 13.0 ± 1.0 Gyr and distance modulus of (m−M)V=15