The Araucaria Project: Multi-band Calibrations of the TRGB Absolute Magnitude

We present new empirical calibrations of the absolute magnitude of the tip of the red giant branch (TRGB) in the optical I and near-infrared J, H, and K bands in terms of the (V − K)0, (V − H)0, and (J − K)0 colors of the red giant branch (RGB). Our calibrations are based on the measurements in 19 fields in the Large and Small Magellanic Clouds, which span a wide (V − K)0 color range of the brightest part of the RGB. We use a simple edge detection technique based on the comparison of the star count difference in two adjacent bins with the estimated Poisson noise. Further, we include the reddening and geometrical corrections, as well as the distance to the Large Magellanic Cloud that is precise and accurate to within 2%. The calibration based on (V − K) colors can be a robust tool to calculate the absolute magnitude of the TRGB with great precision.