  Ruprecht 147 is a hitherto unappreciated open cluster that holds great
promise as a standard in fundamental stellar astrophysics. We have conducted a
radial velocity survey of astrometric candidates with Lick, Palomar, and MMT
observatories and have identified over 100 members, including 5 blue
stragglers, 11 red giants, and 5 double-lined spectroscopic binaries (SB2s). We
estimate the cluster metallicity from spectroscopic analysis, using
Spectroscopy Made Easy (SME), and find it to be [M/H] = +0.07 \pm 0.03. We have
obtained deep CFHT/MegaCam g'r'i' photometry and fit Padova isochrones to the
(g' - i') and 2MASS (J - K) CMDs using the \tau^2 maximum-likelihood procedure
of Naylor (2009), and an alternative method using 2D cross-correlations
developed in this work. We find best fits for isochrones at age t = 2.5 \pm
0.25 Gyr, m - M = 7.35 \pm 0.1, and A_V = 0.25 \pm 0.05, with additional
uncertainty from the unresolved binary population and possibility of
differential extinction across this large cluster. The inferred age is heavily
dependent by our choice of stellar evolution model: fitting Dartmouth and
PARSEC models yield age parameters of 3 Gyr and 3.25 Gyr respectively. At
approximately 300 pc and 3 Gyr, Ruprecht 147 is by far the oldest nearby star
cluster.
