[KIDS] completeness/contamination

[G. Sikkema]

hi Francesco,

thanks for the analysis report on completeness for field KIDS_135_-1.5.
We are currently reprocessing the g,r,i tiles, to see if we can remove 
the satellite tracks.
However, the new satellite code has problems removing very faint 
satellite tracks (at ~2 times the nosie).
So in my opinion, it would be good to set the detection threshold at 
least to 2 and min_area at 5.
Could you also send the source distribution plots (i.e.: 
CONTAMINATION_xy_min3_thre2.0.jpg ) for the following configurations?:
min_area=5 & detect_thresh=2.5
min_area=5 & detect_thresh=2.0
min_area=3 & detect_thresh=2.5

And from what band was your source distrubtion plot derived?
GS



On 02/05/2013 12:51 PM, Francesco La Barbera wrote:
> Dear All,
>
> we performed a more detailed study of completeness/contamination of 
> our KIDS catalogs by comparing
> KIDS vs. CFHT photometry in the field of KIDS_135_-1.5.
>
> Here it's the steps we followed:
>
> 1) We downloaded the last version of the images, that   shouldn't be   
> affected
> by the satellite track issue we found in the previous version of the 
> coadd's.
> 1) We ran KIDSCAT on the r-band images, with 6 different setups, 
> changing DETECTION_MINAREA
> and DETECTION_THRESHOLD in the S-Ex .configuration file. We considered:
> MINAREA: 3, 5
> THRESHOLD: 1.5, 2.0, 2.5
> Besides that, we also ran KIDSCAT on the g and i band images with 
> MINAREA=3, and THRESHOLD=2.0, 2.5
>
>
> 2) The catalogs were matched to the CFHT ones (pls ask Mario for details)
>
> 3) The first attached plot, CFHT_KIDS_....._THRESHOLD.jpg, summarizes 
> the completeness/contamination with different setups for the r-band coadd.
> Top and bottom panels correspond to MINAREA=3 and 5, respectively.
> For each panel, the solid curves plot the fraction of spurious sources 
> (i.e. objects with no matching to CFHT)
> as a function of magnitude. We considered magnitudes in the same 
> aperture of 5'' in both catalogs (KIDS and CFHT).
> Curves with different colors correspond to different 
> DETECTION_THRESHOLDs as labeled.
> The completeness mags, for each THRESHOLD value (i.e. color), are 
> marked with a vertical dashed line.
> (Here completeness is defined as the mag value where CFHT counts keep 
> increasing, while KIDS counts remain constant/decrease).
>
> 4) The second attached plot shows the spatial distribution of spurious 
> sources in the area "previously" affected by the satellite track.
>
> 5) We would conclude as follows:
>  A) for THRESHOLD=1.5 contamination increases significantly, up to 
> ~20-22% around the completeness mag
>  B) completeness improves by ~0.15-0.2mag when moving from THRESHOLD 
> 2.5 to 2.0, and by the same amount from 2.0 to 1.5.
>  C) changing MINAREA to 5 we get slightly lower completeness 
> (by~0.1-0.15mag), and slightly lower contamination (by a few percent)
>  D) the satellite track issue is still there
>
> Depending on what is the maximum level of contamination we can allow 
> in the catalogs, we think we might adopt either THRESHOLD=2.5 (current 
> value)
> or THRESHOLD=2.0, as in the latter value we get slightly better 
> completeness, at the price of a bit worst contamination.
> Notice that the contamination fractions are indeed upper limits (see 
> our previous email on the subject), as there are many sources
> not present in the CFHT catalogs  because of (e.g.) deblending issues.
>
> Finally, the last attached plot, 
>   CFHT_KIDS_COMPLETENESS_CONTAMINATION_THRESHOLD_g_i_bands.jpg, shows 
> completeness and contamination
> for g band (upper panel) and i band (lower panel), both for MINAREA=3. 
> Resuts are similar to those for r band.
>
> Eagerly waiting for your feedback, so that we can finalize the S-Ex 
> configuration file.
>
> Cheers,
> Francesco, Nicola, Mario
>
> -------------------------------------------------------------------------------
>
>
>
> _______________________________________________
> KiDS mailing list
> KiDS at astro-wise.org
> http://listman.astro-wise.org/mailman/listinfo/kids


-- 
dr. Gert Sikkema

Kapteyn Institute
Zernike Building, room 133
P.O. Box 800
9700 AV Groningen
sikkema at astro.rug.nl
homepage: http://www.astro.rug.nl/~sikkema
31-50-3634548
MSN: add: cubensi at hotmail.com to your MSN

* Popular lectures on:
- Einstein's theory of Relativity
- Globular Clusters

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listman.astro-wise.org/pipermail/kids/attachments/20130205/5ae87af9/attachment.html