  Photoelectric spectrophotometry is presented for 237 stars in the Hyades,
Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC~4665, and M39 open
clusters. 16 bandpasses were observed from 350 nm to 778 nm, with 3.2 to 6.4 nm
bandwidth. Data are standardized to the Hayes-Latham system to mutual accuracy
of 0.016 mag per passband. By comparison to SIMBAD-available BV and ubvy colors
on the one hand, and to 1993 Kurucz synthetic spectra on the other, we show our
data to be accurate to 0.01 mag for the 13 passbands at or above 400 nm, and
0.02 mag for the 3 passbands below 400 nm. We also show that the scatter in the
fits of the spectrophotometric colors and the uvby filter colors is a
reasonable way to identify the observations of which specific stars are
accurate to 1-sigma, 2-sigma, ... The very good agreement between the models
and these data verifies the accuracy of these data, and also verifies the
usefulness of the Kurucz models to define spectrophotometry for stars in this
temperature range (>5000 K). These data define accurate spectrophotometry of
bright, open cluster stars that can be used as a secondary flux calibration for
CCD-based spectrophotometric surveys.
