RR Lyrae stars as Reddening Probes: Calibration in the DECam Optical Bandpasses

RR Lyrae variable stars are not only a well established standard candle of old stellar populations, but also, they are extremely good standard colors. These properties make RR Lyrae stars valuable tools in high extinction regions, such as the Galactic Bulge, since it is possible to obtain the line-of-sight reddening if multi-band photometry is available. We present preliminary results of an ongoing project that aims to derive calibrated Color-Period relationships in the optical filters (ugrizY) used by the Dark Energy Camera (DECam) on the Blanco Telescope at CTIO. We obtained multi-band, multi-epoch observations of 12 galactic globular clusters with known populations of RR Lyrae stars, spanning a range of metallicities, location in the Galaxy and Oosterhoff type. The color at minimum light - period relationship is expected to have little or no dependence on metallicity for colors made with the reddest filters (riz), but it may be important for colors containing the bluer bands u or g