RESOLVE Survey Photometry and Volume-limited Calibration of the
  Photometric Gas Fractions Technique
  We present custom-processed UV, optical, and near-IR photometry for the
RESOLVE survey, a volume-limited census of stellar, gas, and dynamical mass
within two subvolumes of the nearby universe (RESOLVE-A and -B), complete down
to baryonic mass ~10^9.1-9.3 Msun. In contrast to standard pipeline photometry
(e.g., SDSS), our photometry uses optimal background subtraction, avoids
suppressing color gradients, and includes systematic errors. With these
improvements, we measure brighter magnitudes, larger radii, bluer colors, and a
real increase in scatter around the red sequence. Combining stellar masses from
our photometry with the RESOLVE-A HI mass census, we create volume-limited
calibrations of the photometric gas fractions (PGF) technique, which predicts
gas-to-stellar mass ratios (G/S) from galaxy colors and optional additional
parameters. We analyze G/S-color residuals vs. potential third parameters,
finding that axial ratio is the best independent and physically meaningful
third parameter. We define a "modified color" from planar fits to G/S as a
function of both color and axial ratio. In the complete galaxy population,
upper limits on G/S bias linear and planar fits. We therefore model the entire
PGF probability density field, enabling iterative statistical modeling of upper
limits and prediction of full G/S probability distributions for individual
galaxies, with two-component structure for red colors. We use the RESOLVE-B
21cm census to test several PGF calibrations, finding that most systematically
under- or overestimate gas masses, but the full probability density method
performs well.
