MCR-TRGB: A Multiwavelength-Covariant, Robust Tip of the Red Giant Branch Measurement Method

Understand

We present a new method to measure colors and magnitudes of the tip of the red giant branch in multiple bandpasses simultaneously by fitting an n-dimensional Gaussian to photometry of candidate tip stars.

• We demonstrate that this method has several advantages over traditional edge detection, particularly in regimes where the TRGB magnitude is strongly color-dependent, as is the case in the near-infrared.
• We apply this method to a re-reduction of a set of optical and near-IR HST data originally presented in Dalcanton et al.
• (2012).