Random Thoughts about non-3band Sources
The "SNR>7 in any one band" criterion permits two and one band sources to enter the the catalog-generation database (and presumably the catalogs if sufficiently bright). Here are the statistics from the working draw from the south1_wsdb. The working draw is called south1_pscat. rd_flg count(*) ====================== 220 35,161 (14%) 202 206 022 1,133 200 5,057 (2%) 020 1,021 002 292 Comments on '220' sources: There is almost always a K-band source visible in these images even though it did not get measured. This means the upper limit aperture photometry likely contains meaningful flux. The color-color diagram constructed from the default psf-fit mags indeed looks like that for real galaxies. The full catalog will contain 15 million of these sources (the test field is about 100 deg sq.), putting the XSC contents to shame....
The diagrams for '202' and '022' sources are not quite as well behaved:
The 022's in particular seem to have a large component of split double stars and broken galaxies. The 202's look better in general. There appears to be an isolate H-band source visible that did not get measured.
Here are some snr stats for these sources. High SNR sources tend to be the ones which result from processing errors. Low SNR sources tend to be real. ra | decl | j_snr | h_snr | k_snr | j_msig | h_msig | k_msig -----------+------------+-------+-------+-------+--------+--------+-------- 72.542018 | -22.612226 | 7.13 | | 5.04 | 0.158 | |0.213 72.554973 | -21.406292 | 6.85 | | 5.32 | 0.152 | |0.214 72.497127 | -21.199888 | 7.52 | | 6.03 | 0.153 | |0.158 72.468105 | -20.98271 | 8.77 | | 4.8 | 0.133 | |0.225 72.460108 | -19.656847 | 7.19 | | 3.24 | 0.165 | |0.349 72.482238 | -19.586666 | 7.47 | | 4.61 | 0.161 | |0.266 72.574328 | -19.293579 | 7.15 | | 3 | 0.152 | |0.344 72.465047 | -23.791426 | 7.87 | | 5.24 | 0.157 | |0.225 72.643818 | -19.482813 | 7.41 | | 6.19 | 0.197 | |0.18 72.59205 | -19.687778 | 13.27 | | 8.36 | 0.144 | |0.142 72.683784 | -20.735416 | 7.33 | | 5.63 | 0.156 | |0.207 72.58596 | -20.909197 | 7.69 | | 5.32 | 0.145 | |0.226 72.657451 | -23.780684 | 7.57 | | 4.93 | 0.159 | |0.208 72.630816 | -18.768475 | 7.2 | | 4.93 | 0.18 | |0.232 72.746842 | -21.065998 | 7.33 | | 4.54 | 0.159 | |0.226 72.814328 | -20.131533 | 7.17 | | 4.12 | 0.15 | |0.276 72.784385 | -19.052425 | 7.03 | | 5.52 | 0.176 | |0.217 72.835415 | -19.030252 | 7.12 | | 3.75 | 0.15 | |0.269 72.725652 | -18.709911 | 7.11 | | 6.39 | 0.164 | |0.182 ============================================================= Effect the of three-band faint extension: wsdb=> select count(*) from south1_pscat; (primary selection) count -------- 250742 (1 row) wsdb=> select count(*) from south1_pscat2; (excludes low snr 3-band) count -------- 242756 (1 row) Here is the blink between the two samples:
====================================================================== What we would get if we included two-band sources to SNR=5 in one band. select count(*) from south1_pscat3 (includes low snr '220' sources) count -------- 277089 (1 row) Gives 26,000 new sources, probably galaxies. (10,000,000 more whole sky).
