  We present optical long-slit rotation curves (RCs) for 304 northern Sb-Sc UGC
galaxies originally selected for Tully-Fisher (TF) applications. 20% of the
galaxies were observed twice or more, allowing for a proper determination of
systematic errors. Various measures of maximum rotational velocity to be used
as input in the TF relation are tested on the basis of their repeatability,
minimization of TF scatter, and match with 21cm linewidths. The best measure of
TF velocity, v2.2, is given at the location of peak rotational velocity of a
pure exponential disk. Optical TF calibrations yield internal scatter
comparable to, if not smaller than, the best calibrations based on single-dish
21cm radio linewidths. Even though resolved HI RCs are more extended than their
optical counterpart, a tight match between optical and radio linewidths exists
since the bulk of the HI surface density is enclosed within the optical radius.
We model the 304 RCs presented here and a sample of 958 curves from Mathewson
etal. (1992) with various fitting functions. An arctan function provides an
adequate simple fit (not accounting for non-circular motions and spiral arms).
More elaborate, empirical models may yield a better match at the expense of
strong covariances. We caution against physical or "universal"
parameterizations for TF applications. (abridged)
