2200 field: K vs I band catalogues

--1 Adding an artificial star image FWHM = 0".8 arcsecs to the
real image (K or I band) the following completeness values are obtained:

From these two plots, 90% completeness values are I_AB = 24.0 and K_Vega = 21.0 .
It should be remembered though that at K_Vega > 21.00 for this field contamination
rate becomes higher than 10%, suggesting that the scientific analysis for the K-band
data in this field should be limited to K_Vega < 21.00.

--2 Number of objects in SExtractor catalogues (in overlapping area, 89.3 sq arcmins,
limits defind here):

I-band --> 4039 in total, 1903 down to I_AB < 24.0 .
K-band --> 5886 in total, 2135 down to K_Vega < 21.0 .

Pairing according to Ra and Dec between the two catalogues results in 2544 objects
in common, 1495 unpaired I-band objects, 3342 unpaired K-band objects.

--3 Magnitude distribution of paired(blue)/unpaired(red)/total(grey) objects in the
I-band and K-band catalogues :

One can see that down to the respective 90% completeness limit the percentage
of paired objects is slightly higher for I-band than for K-band:

I-band --> @ I_AB < 24.0 : 1710 are paired (90%) and 193 are unpaired (10%)
K-band --> @ K_Vega < 21.0: 1697 are paired (79%) and 438 are unpaired (21%)

        A visual inspection of the 438 bright (K_Vega < 21.0), unpaired, K-band objects
        shows that most of these are bona-fide objects with no visible I-band counterparts.
        (click here for an image gallery of interesting cases). Down to K_Vega < 20.75 (78 objs)
        the percentage of reliable K-band unpaired detections is as high as 90%.

           a -- 2544 paired objects: for them the K-band info should simply be added in
                      the database. Here is the file that contains the IDs of these objects in
                      the database and their full K-band Sextractor information (usual format).
                     The K-band photometric info contained in this file should go into the
                      database.

           b -- 1495 unpaired I-band objects: for them in the database we should
                     put Kmag=99.00, meaning no K-band detection. Here is the file that
                     contains the IDs of these objects in the database.

           c -- 3332 unpaired K-band objects: I would keep * only * those with K_Vega < 21.0.
                   These 438 objects should be added to the database. Here is the file that contains
                   their full K-band Sextractor information. In order to attribute to them a sensible
                    I band magnitude, I did run SExtractor on the B-V-I-band image using the K-band
                    image as a reference one, and here are the files (for B, V, and I bands), with the
   full Sextractor information for these objects.