Images and Catalogues
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CFHTLS Deep Field stacked images and catalogues:
This page contains links to the "best seeing" version of the CFHTLS Deep
Fields data. As an alternative to the direct links, use the check
boxes to select multiple data sets and then click on the "Download"
button to use CADC's DownloadManager.
The rationale for which images were included in the best seeing images is discussed here.
Each image covers approximated 1 square degree and measures
roughly 20000x20000 pixels.
All the images for each field are registered with each other:
a pixel of one image in one band covers exactly the same bit of sky as
the equivalent pixel in another image.
All the images have a photometric zero-point of 30.000. That is to say:
Mag = -2.5 *log10 (counts) + 30in AB magnitudes. The naming convention is:
D1.IQ.U.fits ^ ^ ^ | | |___ Filter | |______ Version: this is the good seeing version |_________ Field
These are inverse variance weight maps. They have names like:
D1.IQ.U.weight.fitsThe weight maps are are delivered with in a compressed format. To uncompress them, use CFITSIO's imcopy:
imcopy D1.IQ.U.weight.fits.fz D1.IQ.U.weight.fits
Multiband photometric catalogues:
These catalogues (one per deep field) give photometry in all 5 filters through matched apertures. The detection and aperture determination is done in the I band. That is to say, the catalogues are I-selected. The photometric catalogues are all in ASCII format: The photometric catalogues were generated as described here. The magnitudes are all in AB magnitudes, measured in Kron-style apertures (SExtractor's MAG_AUTO). No corrections have been made for galactic extinction. A magnitude of 99 indicates no measurable flux. The column HLR is the half light radius (in arcseconds) of the object. A value of 99 means that the half light radius could not be measured.
The multiband photometric catalogues have names like
Single-band Photometric Catalogues:
These catalogues contain the photometry and a few image shape paramters determined for each filter individually for each of the deep fields. The columns are labelled and described in each of the ASCII format files: These photometric catalogues were generated by running SExtractor in normal mode on the relevant images as described here. Most of the columns are fairly self explanatory. MAG_APER is the aperture magnitude measured through 3 arcsecond diameter radius. FLUX_RADIUS is the half-light radius. They have names like: