  SCUBA-2, which replaces SCUBA (the Submillimeter Common User Bolometer Array)
on the James Clerk Maxwell Telescope (JCMT) in 2006, is a large-format
bolometer array for submillimeter astronomy. Unlike previous detectors which
have used discrete bolometers, SCUBA-2 has two dc-coupled, monolithic, filled
arrays with a total of ~10,000 bolometers. It will offer simultaneous imaging
of a 50 sq-arcmin field of view at wavelengths of 850 and 450 microns. SCUBA-2
is expected to have a huge impact on the study of galaxy formation and
evolution in the early Universe as well as star and planet formation in our own
Galaxy. Mapping the sky to the same S/N up to 1000 times faster than SCUBA, it
will also act as a pathfinder for the new submillimeter interferometers such as
ALMA. SCUBA-2's absorber-coupled pixels use superconducting transition edge
sensors operating at 120 mK for performance limited by the sky background
photon noise. The monolithic silicon detector arrays are deep-etched by the
Bosch process to isolate the pixels on silicon nitride membranes. Electrical
connections are made through indium bump bonds to a SQUID time-domain
multiplexer (MUX). We give an overview of the SCUBA-2 system and an update on
its status, and describe some of the technological innovations that make this
unique instrument possible.
