  This is the third in a series of papers in which spiral galaxy rotation
curves are considered in the context of Milgrom's modified dynamics (MOND). The
present sample of 30 objects is drawn from a complete sample of galaxies in the
Ursa Major cluster with photometric data by Tully et al. (1996) and 21 cm line
data by Verheijen (1997). The galaxies are roughly all at the same distance (15
to 16 Mpc). The radio observations are made with the Westerbork Synthesis Array
which means that the linear resolution of all rotation curves is comparable.
The greatest advantage of this sample is the existance of K'-band surface
photometry for all galaxies; the near-infrared emission, being relatively free
of the effects of dust absorption and less sensitive to recent star formation,
is a more precise tracer of the mean radial distribution of the dominant
stellar population. The predicted rotation curves are calculated from the
K'-band surface photometry and the observed distribution of neutral hydrogen
using the simple MOND prescription where the one adjustable parameter is the
mass of the stellar disk or the implied mass-to-light ratio. The predicted
rotation curves generally agree with the observed curves and the mean M/L in
the near-infrared is about 0.9 with a small dispersion. The fitted M/L in the
B-band is correlated with B-V color in the sense predicted by population
synthesis models. Including earlier work, about 80 galaxy rotation curves are
now well-reproduced from the observed distribution of detectable matter using
the MOND formula to calculate the gravitational acceleration; this lends
considerable observational support to Milgrom's unconventional hypothesis.
