[KIDS] CFHT completeness tests

[Francesco La Barbera]

Dear All,

we have tested our internal completeness estimates (KIDSCATv1.5) wrt the
CFHT vs. KIDS number counts, over the (overlapping) area of coadd 135_-1.5.

Pls, find attached here the four plots corresponding to u, g, r, and i
wavebands.
Each plot consists of two panels. The upper panel compares the KIDS-CFHT
MAG_AUTOs. Notice that at "faint" mags, KIDS MAG_AUTO is too faint, likely
because S-Ex underestimates the Kron radius at faint flux levels (but we
should also
check if CFHT people used the same S-Ex MAG_AUTO parameters as we do).
Pls, see Mario last emails about details on the CFHT-KIDS matched catalogs.

The KIDS MAG_AUTOs are corrected with the median trends in the upper panels,
bringing them to the CFHT system.

The bottom panels  compare the resulting number counts (we selected *all*
sources, with good
flag values) between KIDS (black) and CFHT (red). We (eyeball) defined a
"true" compleness,
i.e. the magnitude where CFHT number counts keep increasing, while KIDS
counts start dropping down.
The true completeness values are marked by the blue vertical lines, while
our KIDSCAT completeness is marked by the green vertical line in each plot.

As you can see, the agreement is remarkable, within 0.1mag for gri, and
somewhat worst
(~0.2mag) for u band. Pls keep in mind that the MAG_AUTO correction for u
band
is also quite uncertain (see the corresponding top panel).

We are working now to establish the fraction of spurious sources, and see
how this fraction as well as the completeness itself change
when varying the detection threshold used to create the catalogs. This
should allow us to optimize
detection parameters for ESO-DR1.
Also, looking at the dispersion of delta(mags), we can test if our KIDS mag
errors are realistic, and thus if the
magnitude limits are reliable too.


Cheers,
Francesco, Nicola, Mario
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