The 0.5 x 0.5 degree area surrounding the Chandra Deep Field South (the GEMS/MUSYC "Extended" CDFS, or E-CDFS) has excellent multi-wavelength data from X-rays to the infrared. SIMPLE has added deep Spitzer/IRAC observations.

The main science applications are to select massive galaxies at high redshift, to disentangle contributions from age, dust, and AGNs to their broad band SEDs, and to study the host galaxies of AGNs.