Dear All,<div><br></div><div>here it's some updates about completeness/contamination estimates in the CFHT overlap area, based</div><div>on the matched catalog produced by Mario.</div><div><br></div><div>The first attached plot is an updated version of what we have sent yesterday, but now we also plot the fraction</div>
<div>of spurious sources, i.e. contamination, as a function (KIDSCAT) MAG_AUTO in the bottom panel</div><div>of the same figure.</div><div>The fraction of "candidate spurious" is defined as the ratio </div><div>
#OBJECTS_NOT_MATCHED_WITH_CFHT/#OBJECTS_MATCHED</div><div><br></div><div>The difference between the black adn red curve (bottom panel) is that for the red curve I selected only KIDSCAT detections</div><div>with SEX_FLAG==0|SEXFLAG>=16, hence removing sources blended with other objects.</div>
<div>As you can see most of "candidate spurious" sources at bright mags (they are not spurious, indeed, see below) have been</div><div>deblended by S-Ex.</div><div><br></div><div>The second attached plot shows the spatial distribution of spurious sources, black and red colors have the same meaning as </div>
<div>above. There are clearly some spurious features (e.g. detections along a residual satellite track),</div><div>but in most cases (pls, compare black vs. red dots), the "candidate spurious" objects are actually deblended sources.</div>
<div><br></div><div>The third attached plot shows the spatial distribution of "candidate spurious" (black circles) in a region around a bright star</div><div>(pixel coordinates x~25000, y~10000). Most of the objects are true sources!! and they are actually missing in the</div>
<div>CFHT catalog (maybe, they were just masked out by the CFHT masks).</div><div><br></div><div>Another example is the last attached file, contamination_2.jpg, where you can clearly see "true spurious" objects</div>
<div>along a residual satellite track. Other "spurious" are just S-Ex blends.</div><div><br></div><div>To summarize:</div><div>1) completeness estimates within KIDSCAT seem to work OK, at least for this field where we have an external comparison;</div>
<div>2) for what concerns the objects present only in the KIDS image (not in the CFHT one), i.e. the possible spurious, we have the following cases:</div><div> A) most of them are *true* sources, close to brighter companions, likely detected only in KIDS because of the better seeing wrt CFHT;</div>
<div> B) some of these "true" sources are not present in the CFHT catalog as they were probalby masked out, for some reason, in CFHT;</div><div> C) finally, we have "true" contaminants, mostly associated to satellite tracks, still present in the KIDS image.</div>
<div>3) as a result, the red curve in bottom panel of Fig.~CFHT_KIDS_COMPLETENESS_CONTAMINATION_135_-1.5_r.jpg gives </div><div>an **upper** estimate of contamination in this r-band image. Contamination is <~2% at bright mags (<23), increasing to at most</div>
<div>10% at faint mags (~24.5-25).</div><div><br></div><div>Now, Nicola is producing catalogs for different values of DETECTION_MINAREA and THRESHOLD. Mario will match them again, and then we can test </div><div>how contamination/completeness change as a function of detection parameters.</div>
<div><br></div><div>Cheers,</div><div>Francesco</div><div><br></div><div><br></div>