The Next Generation Virgo Cluster Survey (NGVS). XVIII. Measurement and
  Calibration of Surface Brightness Fluctuation Distances for Bright Galaxies
  in Virgo (and Beyond)
  We describe a program to measure surface brightness fluctuation (SBF)
distances to galaxies observed in the Next Generation Virgo Cluster Survey
(NGVS), a photometric imaging survey covering $104~deg^2$ of the Virgo cluster
in the ${u}^*,g,i,z$ bandpasses with the Canada-France Hawaii Telescope. We
describe the selection of the sample galaxies, the procedures for measuring the
apparent $i$-band SBF magnitude $\bar{i}$, and the calibration of the absolute
$\bar{M}_i$ as a function of observed stellar population properties. The
multi-band NGVS data set provides multiple options for calibrating the SBF
distances, and we explore various calibrations involving individual color
indices as well as combinations of two different colors. Within the color range
of the present sample, the two-color calibrations do not significantly improve
the scatter with respect to wide-baseline, single-color calibrations involving
$u^{*}$. We adopt the ${u}^*{-}z$ calibration as reference for the present
galaxy sample, with an observed scatter of 0.11 mag. For a few cases that lack
good ${u}^*$ photometry, we use an alternative relation based on a combination
of $g{-}i$ and $g{-}z$ colors, with only a slightly larger observed scatter of
0.12 mag. The agreement of our measurements with the best existing distance
estimates provides confidence that our measurements are accurate. We present a
preliminary catalog of distances for 89 galaxies brighter than $B_T\approx13.0$
mag within the survey footprint, including members of the background M and W
Clouds at roughly twice the distance of the main body of the Virgo cluster. The
extension of the present work to fainter and bluer galaxies is in progress.
