CFHT optical & NIR obs. of RR Lyrae in M15

We report new optical (gi) and near-infrared (NIR, JKs) multi-epoch observations for 129 RR Lyrae, 4 Population II Cepheids (3 BL Herculis, 1 W Virginis), and 1 anomalous Cepheid variable candidate in M15 obtained using the MegaCam and the WIRCam instruments on the 3.6m Canada-France-Hawaii Telescope.

Multi-band data are used to improve the periods and classification of variable stars, and determine accurate mean magnitudes and pulsational amplitudes from the light curves fitted with optical and NIR templates. We derive optical and NIR period-luminosity relations for RR Lyrae stars which are best constrained in the Ks band, m_Ks_=-2.333(0.054)logP+13.948(0.015) with a scatter of only 0.037mag. Theoretical and empirical calibrations of RR Lyrae period-luminosity-metallicity relations are used to derive a true distance modulus to M15: 15.196+/-0.026 (statistical) +/-0.039(systematic) mag.