The state-of-the-art in wide-field imaging at CFHT
MegaPrime/MegaCam is the wide-field optical imaging facility at CFHT. It
represented a major upgrade of the telescope upper-end as well as the largest
astronomical CCD mosaic ever built at the time of the official first light in
January 2003 and for many years that followed.
The wide-field imager, MegaCam (built by CEA, Saclay, France),
consists of 36 2048 x 4612 pixel CCDs (a total of 340 megapixels),
covering a full 1 x 1 square degree field-of-view with a resolution of
0.187 arcsecond per pixel to properly sample the 0.7 arcsecond median seeing
offered by the CFHT at Mauna Kea. The new prime focus upper end, MegaPrime,
includes an image stabilization unit and a guide/autofocus unit with two
independent guide CCD detectors.
MegaCam is an optical & near infrared instrument mounted on the telescope
for 10 to 18 days periods centered on the new Moon. It uses most of the telescope
dark time to conduct Principal Investigators led scientific programs as well as
large programs or surveys such as the CFHT Legacy Survey
which represented a total of 450 nights over five years between 2003 and 2009.
MegaPrime/MegaCam is operated exclusively through the CFHT New Observing
Process (NOP). Observations are carried out through Queued Service
Observing (QSO), the data are pre-processed (removal of the instrumental
signature) and calibrated (photometry and astrometry) by Elixir, and
eventually made available online to the Principal Investigators through the
Data Archiving & Distribution System (DADS). The raw and Elixir pre-processed
data are archived at the Canadian Astronomy Data Centre (CADC) in Victoria, and
become public after a one year proprietary period. The Terapix data processing
center based in Paris, primarily focused on handling the CFHTLS data, also
proposes its services to the whole CFHT community with the MegaCam data
stacking, fine astrometric calibration and catalogs generation.
MegaPrime is a CFHT project, funded through the instrumentation fund
by the Canadian and French Agencies (NRC and CNRS/INSU). The
Observatoire de Paris and HIA (Victoria) have been contracted for
the design and fabrication of some of the MegaPrime components.
MegaCam was built in France by CEA (Saclay). The section
covers in detail the various parts of the instrument and the entities
responsible for building them.
Note to the Principal Investigators preparing a time proposal:
all the information relevant to the preparation of a time proposal
and/or preparing the time distribution for the QSO's PH2 phase can be
found in the "Specifications & Performance" and "Observing Process"
sections in the left menu (instrument specifications, exposure time