  The Cygnus OB2 association is the largest concentration of young and massive
stars within 2 kpc of the Sun, including an estimated 65 O-type stars and
hundreds of OB stars. The Chandra Cygnus OB2 Legacy Survey is a large imaging
program undertaken with the Advanced CCD Imaging Spectrometer onboard the
Chandra X-ray Observatory. The survey has imaged the central 0.5 deg^2 of the
Cyg OB2 association with an effective exposure of 120ks and an outer 0.35 deg^2
area with an exposure of 60ks. Here we describe the survey design and
observations, the data reduction and source detection, and present a catalog of
8,000 X-ray point sources. The survey design employs a grid of 36 heavily
(~50%) overlapping pointings, a method that overcomes Chandra's low off-axis
sensitivity and produces a highly uniform exposure over the inner 0.5 deg^2.
The full X-ray catalog is described here and is made available online.
