Near-Infrared Observations of RR Lyrae variables in Galactic Globular   Clusters: I. The case of M92
  We present near-infrared J,H, and K-band time series observations of the Galactic Globular Cluster (GGC) M92. On the basis of these data, we derived well-sampled light curves for eleven out of the seventeen cluster RR Lyrae variables, and in turn, accurate mean near-infrared (NIR) magnitudes. The comparison between predicted and empirical slopes of NIR Period-Luminosity (PL) relations indicates a very good agreement. Cluster distance determinations based on independent theoretical NIR $PL$ relations present uncertainties smaller than 5% and agree quite well with recent distance estimates based on different distance indicators. We also obtained accurate and deep NIR color-magnitude diagrams (CMDs) ranging from the tip of the Red Giant Branch (RGB) down to the Main Sequence Turn-Off. We detected the RGB bump and the NIR luminosities of this evolutionary feature are, within theoretical and empirical uncertainties, in good agreement with each other. 
M. Del Principe (1), A. M. Piersimoni (1), G. Bono (2), A. Di Paola   (2), M. Dolci (1), M. Marconi (3) ((1)INAF - Osservato...