<div>Dear All,</div><div><br></div><div>I summarize here the comparison of KIDS to SDSS photometry we</div><div>(Mario+me) have performed so far for the 52 coadds of KIDS INTR2. All</div><div>plots are included in the attached archive.</div>
<div><br></div><div>Mario has also performed a comparison to CFHTLS as well as a first</div><div>attempt to characterize of color terms using SDSS and CFHTLS data, but</div><div>I'm not going to include it in here (we didn't have much time to look</div>
<div>at it in detail, so far).</div><div><br></div><div>We have matched the KIDSCAT catalogs to SDSS DR8, separating stars and</div><div>galaxies according to SDSS classification.</div><div><br></div><div>The plots</div><div>
<br></div><div>sdss_${SOURCE}_${BAND}_${FIELD}_full_DR8.png </div><div><br></div><div>show differences in magnitude as a function of RA (upper panel) and</div><div>DEC (lower panel), where </div><div>SOURCES -> gal/st refer to galaxies and stars, respectively</div>
<div>BAND -> ugri</div><div>FIELD -> f135 plots the three fields with RA~131, 135, and 139</div><div> f185 plots the ten fields with RA~184, 185, and 186</div><div><br></div><div>We are using petromags from SDSS (for both stars and galaxies).</div>
<div>KIDSCAT mags have been interpotaled to match the SDSS 4xPetroRad</div><div>(diameter) aperture for each object. Lines are running medians for</div><div>different bands/pointings (the u-band comparison for galaxies is quite</div>
<div>meaningless, considering the low S/N of SDSS u-band data). Median</div><div>KIDS-SDSS offsets have been subtracted off for each field.</div><div><br></div><div>On average, the agreement is good, with no significant variations</div>
<div>(larger than a few cenths of mags) across the fields. This is further</div><div>shown in the attached plots</div><div><br></div><div>cmp_${BAND}band_phot_ra_dec_${SOURCES}_errmag0.05.jpg</div><div><br></div><div>where </div>
<div><br></div><div>BAND->ugri</div><div>SOURCES-> stars/galaxies</div><div><br></div><div>plotting magntiude differences as a function of RA and DEC with all</div><div>fields overplotted (after subtracting off the RA and DEC of each coadd</div>
<div>center). Median magnitude offsets have been removed (as done for</div><div>previous plots), and only objects with better SDSS photometry</div><div>(petroerr_mag<0.05mag) have been selected. Circles plot all available</div>
<div>sources (for all 13 coadds in each band). Curves are median-binned</div><div>trends (each bin including the same number of objects), with different</div><div>colors corresponding to different fields. Notice that the u-band plot</div>
<div>for galaxies is not included, for the reasons mentioned above.</div><div><br></div><div>Finally, the plots </div><div><br></div><div>off_${BAND}band_phot_ra_dec_${SOURCES}_errmag0.05.jpg</div><div><br></div><div>show the distribution of median magnitude offsets for all the 13</div>
<div>fields available in each band. In general, the distributions have a</div><div>width of a few cenths of mags, but in one case (KIDS_185.0_-0.5,</div><div>g-band) there is a large offset of ~0.1mag. We think it's important to</div>
<div>investigate why this happened.</div><div><br></div><div>I'm also attaching two tables (produced by Mario, hopefully in wiki</div><div>format) summarizing the the median offsets, mad, and peak to peak</div>
<div>amplitudes in RA and DEC (to have an upper value to the internal</div><div>photometric accuracy):</div><div><br></div><div>ov_sdss_gals.tab</div><div>ov_sdss_stars.tab</div><div><br></div><div>If necessary, I can provide further details/info on the comparison</div>
<div>during today's teleconf. We'll try to put all this material on the wiki as</div><div>soon as possible.</div><div><br></div><div>Cheers,</div><div>Francesco & Mario</div><div><br></div>