  The next generation of exoplanet-hunting spectrographs should deliver up to
an order of magnitude improvement in radial velocity precision over the
standard 1 m/s state of the art. This advance is critical for enabling the
detection of Earth-mass planets around Sun-like stars. New calibration
techniques such as laser frequency combs and stabilized etalons ensure that the
instrumental stability is well characterized. However, additional sources of
error include stellar noise, undetected short-period planets, and telluric
contamination. To understand and ultimately mitigate error sources, the
contributing terms in the error budget must be isolated to the greatest extent
possible. Here, we introduce a new high cadence radial velocity program, the
EXPRES 100 Earths program, which aims to identify rocky planets around bright,
nearby G and K dwarfs. We also present a benchmark case: the 62-d orbit of a
Saturn-mass planet orbiting the chromospherically quiet star, HD 3651. The
combination of high eccentricity (0.6) and a moderately long orbital period,
ensures significant dynamical clearing of any inner planets. Our Keplerian
model for this planetary orbit has a residual RMS of 58 cm/s over a $\sim 6$
month time baseline. By eliminating significant contributors to the radial
velocity error budget, HD 3651 serves as a standard for evaluating the long
term precision of extreme precision radial velocity (EPRV) programs.
