The NIR tip of RGB. I. JHK photometry of IC1613

We employ metallicity- independent (rectified) T-band magnitudes-constructed using J-, H-, and K-band magnitudes and both (J-H) and (J-K) colors to flatten the upward-sloping red giant branch tips as otherwise seen in their apparent color-magnitude diagrams.

We describe and quantify the advantages of working at these particular near-infrared wavelengths, which are applicable to both the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST). We also note that these same wavelengths can be accessed from the ground for an eventual tie-in to Gaia for absolute astrometry and parallaxes to calibrate the intrinsic luminosity of the TRGB. Adopting the color terms derived from the IC 1613 data, as well as the zero points from a companion study of the Large Magellanic Cloud, whose distance is anchored to the geometric distances of detached eclipsing binaries, we find a true distance modulus of 24.32+/-0.02 (statistical) +/-0.05mag (systematic) for IC 1613, which compares favorably with the recently published multi-wavelength, multi-method consensus modulus of 24.30+/-0.05mag by Hatt et al. (2017, J/ApJ/845/146).