  The NASA Discovery mission EPOXI, utilizing the Deep Impact flyby spacecraft,
comprises two phases: EPOCh (Extrasolar Planet Observation and
Characterization) and DIXI (Deep Impact eXtended Investigation). With EPOCh, we
use the 30-cm high resolution visible imager to obtain ultraprecise photometric
light curves of known transiting planet systems. We will analyze these data for
evidence of additional planets, via transit timing variations or transits; for
planetary moons or rings; for detection of secondary eclipses and the
constraint of geometric planetary albedos; and for refinement of the system
parameters. Over a period of four months, EPOCh observed four known transiting
planet systems, with each system observed continuously for several weeks. Here
we present an overview of EPOCh, including the spacecraft and science goals,
and preliminary photometry results.
