We are studying the Cygnus OB2 association in order to gain insights into the workings of a massive star forming region. At 1.4 kpc, it is the closest such region to usThe main driver for this is a large, million second Chandra X-ray survey of the young stellar content. In order to help understand the types of stars Chandra is seeing, we need to get observations in the optical and infrared. The Spitzer Space Telescope already made an infrared survey of the region, but optical data were not deep enough for our purposes. We used the 10.4 metre Gran Telescopio Canarias of the Los Muchachos Observatory on La Palma in the Canary Islands to survey the region down to 25th magnitude in the r'
band. The figure shows the extent of the Chandra survey and our GTC survey made using the OSIRIS instrument. As well as detecting 63,556 stars with good photometry, we were also able to measure the extinction caused by dust and gas in the cluster and foreground. We discovered a cloud of material in the foreground lying at a distance of about 850 pc. This work was lead by postdoc Mario Guarcello and was published in the 2012 October edition of the Astrophysical Journal Supplement Series.