  The Hyades K2V+WD system 471 Tau is a prototype post-common envelope system
and a likely cataclysmic binary progenitor. We present 10 days of nearly
continuous optical photometry by the MOST (Microvariability & Oscillations of
STars) satellite and partly simultaneous optical spectroscopy from DDO (David
Dunlap Observatory) of the binary. The photometric data indicate that the spot
coverage of the K dwarf component was less than observed in the past,
suggesting that we monitored the star close to a minimum in its activity cycle.
Despite the low spot activity, we still detected seven flare-like events whose
estimated energies are among the highest ever observed in V471 Tau and whose
times of occurrence do not correlate with the binary orbital phase. A detailed
O-C analysis of the times of eclipse over the last ~35 years reveals timing
variations which could be explained in several ways, including perturbations by
an as-yet-undetected third body in the system or by a small orbital
eccentricity inducing slow apsidal motion. The DDO spectra result in improved
determinations of the K dwarf projected rotation velocity, V_K sin i = 92 km
s^-1, and the orbital amplitude, K_K=150.5 km s^-1. The spectra also allow us
to measure changes in H_alpha emission strength and radial velocity (RV)
variations. We measure a larger H_alpha velocity amplitude than found
previously suggesting that the source of the emission in V471 Tau was less
concentrated around the sub-white-dwarf point on the K star than had been
observed in previous studies.
