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Dear Francesco,
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Thanks for these promising results. The small fraction of spurious detections for DETECT_THRESH=2.5 is promising to test lower detection thresholds.
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I cannot see the bright satellite residual in the KiDS_131.0_-1.5 coadds ready for quality assessment for KiDS-ESO-DR1:
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You can access those using the link posted at http://wiki.astro-wise.org/projects:kids:data_deliveries:kids-eso-dr1:sourcelists#comparison_to_cfhtls-w2.
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Can you confirm?
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If so, I propose we start using those frames for the CFHTLS-W2 comparison.
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Best wishes, Gijs
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<br />
On Thu, 31 Jan 2013 11:57:07 +0100, Francesco La Barbera wrote:
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<blockquote style="padding-left: 5px; border-left: 2px solid #1010ff; margin-left: 5px; width: 100%">
        Dear All,
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        here it's some updates about completeness/contamination estimates in the CFHT overlap area, based
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        on the matched catalog produced by Mario.
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        The first attached plot is an updated version of what we have sent yesterday, but now we also plot the fraction
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        of spurious sources, i.e. contamination, as a function (KIDSCAT) MAG_AUTO in the bottom panel
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        of the same figure.
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        The fraction of "candidate spurious" is defined as the ratio
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        #OBJECTS_NOT_MATCHED_WITH_CFHT/#OBJECTS_MATCHED
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        The difference between the black adn red curve (bottom panel) is that for the red curve I selected only KIDSCAT detections
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        with SEX_FLAG==0|SEXFLAG>=16, hence removing sources blended with other objects.
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        As you can see most of "candidate spurious" sources at bright mags (they are not spurious, indeed, see below) have been
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        deblended by S-Ex.
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        The second attached plot shows the spatial distribution of spurious sources, black and red colors have the same meaning as
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        above. There are clearly some spurious features (e.g. detections along a residual satellite track),
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        but in most cases (pls, compare black vs. red dots), the "candidate spurious" objects are actually deblended sources.
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        The third attached plot shows the spatial distribution of "candidate spurious" (black circles) in a region around a bright star
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        (pixel coordinates x~25000, y~10000). Most of the objects are true sources!! and they are actually missing in the
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        CFHT catalog (maybe, they were just masked out by the CFHT masks).
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        Another example is the last attached file, contamination_2.jpg, where you can clearly see "true spurious" objects
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        along a residual satellite track. Other "spurious" are just S-Ex blends.
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        To summarize:
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        1) completeness estimates within KIDSCAT seem to work OK, at least for this field where we have an external comparison;
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        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:
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         A) most of them are *true* sources, close to brighter companions, likely detected only in KIDS because of the better seeing wrt CFHT;
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         B) some of these "true" sources are not present in the CFHT catalog as they were probalby masked out, for some reason, in CFHT;
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         C) finally, we have "true" contaminants, mostly associated to satellite tracks, still present in the KIDS image.
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        3) as a result, the red curve in bottom panel of Fig.~CFHT_KIDS_COMPLETENESS_CONTAMINATION_135_-1.5_r.jpg gives
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        an **upper** estimate of contamination in this r-band image. Contamination is <~2% at bright mags (<23), increasing to at most
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        10% at faint mags (~24.5-25).
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        Now, Nicola is producing catalogs for different values of DETECTION_MINAREA and THRESHOLD. Mario will match them again, and then we can test
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        how contamination/completeness change as a function of detection parameters.
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        Cheers,
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        Francesco
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