HESS J0632+057 is a variable , point-like source of Very High Energy ( > 100 GeV ) gamma-rays located in the Galactic plane .
It is positionally coincident with a Be star , it is a variable radio and X-ray source , has a hard X-ray spectrum , and has low radio flux .
These properties suggest that the object may be a member of the rare class of TeV/X-ray binary systems .
The definitive confirmation of this would be the detection of a periodic orbital modulation of the flux at any wavelength .
We have obtained Swift X-ray telescope observations of the source from MJD 54857 to 55647 ( Jan. 2009 - Mar .
2011 ) to test the hypothesis that HESS J0632+057 is an X-ray/TeV binary .
We show that these data exhibit flux modulation with a period of 321 \pm 5 days and we evaluate the significance of this period by calculating the null hypothesis probability , allowing for stochastic flaring .
This periodicity establishes the binary nature of HESS J0632+057 .