  The Milky Way contains hundreds of binary systems which are known to emit in
radio and X-rays, but only a handful of binaries have been observed to produce
very high-energy gamma rays. In addition, the emission mechanisms which produce
the gamma rays in the few known sources are not well understood. To improve the
statistics of binary sources in the TeV band, the High-Altitude Water Cherenkov
Gamma-ray Observatory, or HAWC, has begun to carry out a simultaneous survey of
TeV binary candidates in the Northern Hemisphere between 100 GeV and 100 TeV.
HAWC is a surface array that records air showers from cosmic rays and gamma
rays with a high uptime and wide field of view, making it well-suited to
observe time-dependent emission from objects such as TeV binaries. We describe
the sensitivity of HAWC to periodic emission from Galactic sources of gamma
rays and present data from the first year of observations with the partially
constructed observatory.
