  The Multiwavelength Survey by Yale-Chile (MUSYC) is optimized for the study
of galaxies at z=3, AGN demographics, and Galactic structure. MUSYC consists of
deep optical (UBVRIz') and near-infrared (JHK) imaging of four fields on the
sky covering 1.2 square degrees to AB limiting depths of U,B,V,R=26 and K=22.
Our optical catalog contains 277,341 objects detected in BVR images with median
seeing of 0.9''. Satellite coverage of our fields includes Chandra, XMM, GALEX,
HST-ACS, and Spitzer, with the Extended Chandra Deep Field South imaged at all
of these wavelengths plus the radio, making it the premier multiwavelength
field on the sky. Detailed follow-up spectroscopy is being performed with
VLT+VIMOS, Magellan+IMACS and Gemini+GNIRS. MUSYC provides ideal supporting
data for surveys with Z-Machines and rich target lists for spectroscopy with
ALMA. We are conducting a census of protogalaxies at redshift three (Lyman
break galaxies, Lyman-alpha emitters, Distant red galaxies, Sub-millimeter
galaxies and AGN) in order to separate physical properties from selection
effects. We discuss measurements of the dark matter halo masses and halo
occupation numbers of these populations and of the total cosmic star formation
rate at z=3. MUSYC publications and data releases are available at
http://www.astro.yale.edu/MUSYC .
