This collection of pages aims at providing the scientists interested in the CFHT Legacy Survey
a large set of information to follow the progress of the survey from the point of view of
the data acquired at CFHT using the MegaPrime imager equiped with the MegaCam camera.
The main sections of this site (left menu) provide a wide and complete overview of the status
of the CFHTLS: from the observing calendar to the Elixir data releases, various
statistics on the survey, an up-to-date summary of the instrument's history,
a swirl of catalogs listing the exposure acquired, a full description of the raw and Elixir
pre-processed data (pages common with the MegaPrime/MegaCam pages), and the MetaData pages.
MegaPrime/MegaCam is operated exclusively through the CFHT New Observing
Process (NOP) composed of QSO, Elixir & DADS. CFHTLS observations (along with regular
PI observations) are carried out through Queued Service Observing (QSO), the data are preprocessed (removal of the instrumental
signature) and calibrated (photometry and astrometry at the CCD level) by Elixir, and
sent to the Canadian Astronomy Data Centre (CADC) in Victoria on tapes by the
Data Archiving & Distribution System (DADS). The raw data are also archived
at the CADC. The Elixir data are then transfered via the network from CADC
to the Terapix data processing center based in Paris.
Terapix is primarily focused on handling the CFHTLS data and provides its
services to the whole CFHTLS community with the production of
the weight and flag map images attached to each megacam image, the data
stacking, fine astrometric calibration, and source catalogs generation.
Any CFHTLS registered user is free to download the Elixir data made available
at CADC if that user feels confident coping with the data (each image is 700 Mbytes large...).
It may however be wise for the ones not experienced in large CCD mosaic data handling
to wait for the Terapix data products which are based on an evolved ingestion of the Elixir
data, as long as the extra 4 to 5 months needed to get the Terapix data product created and
made available at CADC aren't too much of a constraint of course.
The Elixir data come from CFHT along with the MetaData, a large collection of auxiliary data related
to the observing process: weather statistics, observer comments, sky transparency for the
night, etc... These MetaData are usually sent to the PIs in the form of a CD they can
consult through a browser, but for the Legacy Survey the CFHT proposes these pages
directly accessible on the web since that information is open to the world (the only
elements not made available outside the CFHTLS community are the FITS pixel data, everything
else is fully open).
The proprietary period for the CFHTLS pixel data is 3 years for the first year of operation,
two years for the second year, and one year for the following years. The survey officially
started in mid 2003 and the first pixel data will be made public to the world in August 2006.