  This study is a part of the Cosmicflows-4 project with the aim of measuring
the distances of more than ~10,000 spiral galaxies in the local universe up to
~15,000 km/s. New HI linewidth information has come primarily from the Arecibo
Legacy Fast ALFA Survey. Photometry of our sample galaxies has been carried out
in optical (SDSS u, g, r, i, z) and infrared (WISE W1 and W2) bands.
Inclinations have been determined using an online graphical interface
accessible to a collaboration of citizen scientists. Galaxy distances are
measured based on the correlation between the rotation rate of spirals and
their absolute luminosity, known as the Tully-Fisher Relation (TFR). In this
study, we present the calibration of the TFR using a subsample of ~600 spirals
located in 20 galaxy clusters. Correlations among such observables as color,
surface brightness, and relative HI content are explored in an attempt to
reduce the scatter about the TFR with the goal of obtaining more accurate
distances. A preliminary determination of the Hubble constant from the
distances and velocities of the calibrator clusters is
H0=76.0+-1.1(stat.)+-2.3(sys.) km/s/Mpc.
