  We present a catalogue of 1696 X-ray sources detected in the massive star
forming region (SFR) Cygnus OB2 and extracted from two archival Chandra
observations of the center of the region. A deep source extraction routine,
exploiting the low background rates of Chandra observations was employed to
maximize the number of sources extracted. Observations at other wavelengths
were used to identify low count-rate sources and remove likely spurious
sources. Monte Carlo simulations were also used to assess the authenticity of
these sources. We used a Bayesian technique to identify optical or near-IR
counterparts for 1501 (89%) of our sources, using deep observations from the
INT Photometric H-alpha Survey, the Two Micron All Sky Survey, and the UKIRT
Infrared Deep Sky Survey-Galactic plane Survey. 755 (45%) of these objects have
six-band r', H-alpha, i', J, H, and K optical and near-IR photometry. From an
analysis of the Poisson false-source probabilities for each source we estimate
that our X-ray catalogue includes < 1% of false sources, and an even lower
fraction when only sources with optical or near-IR associations are considered.
A Monte Carlo simulation of the Bayesian matching scheme allows this method to
be compared to more simplified matching techniques and enables the various
sources of error to be quantified. The catalogue of 1696 objects presented here
includes X-ray broad band fluxes, model fits, and optical and near-IR
photometry in what is one of the largest X-ray catalogue of a single SFR to
date. The high number of stellar X-ray sources detected from relatively shallow
observations confirms the status and importance of Cygnus OB2 as one of our
Galaxy's most massive SFRs.
