Measuring Infrared Surface Brightness Fluctuation Distances with HST
  WFC3: Calibration and Advice
  We present new calibrations of the near-infrared surface brightness
fluctuation (SBF) distance method for the F110W (J) and F160W (H) bandpasses of
the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the Hubble Space
Telescope. The calibrations are based on data for 16 early-type galaxies in the
Virgo and Fornax clusters observed with WFC3/IR and are provided as functions
of both the optical (g-z) and near-infrared (J-H) colors. The scatter about the
linear calibration relations for the luminous red galaxies in the sample is
approximately 0.10 mag, corresponding to a statistical error of 5% in distance.
Our results imply that the distance to any suitably bright elliptical galaxy
can be measured with this precision out to about 80 Mpc in a single-orbit
observation with WFC3/IR, making this a remarkably powerful instrument for
extragalactic distances. The calibration sample also includes much bluer and
lower-luminosity galaxies than previously used for IR SBF studies, revealing
interesting population differences that cause the calibration scatter to
increase for dwarf galaxies.
