The WIRCam preprocessed data distributed by CFHT consists in two sets of
the same images: 1) ??????p.fits images are fully preprocessed and sky
subtracted images; 2) ??????s.fits images are fully preprocessed but NOT sky
subtracted images. Distributing the ??????s.fits images allows the PI or
Terapix to fine-tune their sky subtraction technique. For example, Terapix uses
the CFHT set of ??????p.fits images to construct a first-pass deep stack that
is then used to identify faint sources which are then masked in the CFHT
??????s.fits data set to produce second-pass ??????p.fits images required to
construct a final second-pass deep stack. This process is called a two-pass sky
subtraction technique.
We expect to deliver even more meta-data in the future like
SExtractor/2MASS cross-matched catalogues, seeing measurements, NIR absorption
plots, etc.
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