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6.4 The QualityFITS input and output products QualityFITS is a Terapix quality assessment tool for FITS images. During CFHTLS T0007 production, it is used to assess whether individual CFHT input images and the CFHTLS output stacks meet the survey specifications. QualityFITS also produces the input weight-map images as well as the input .ldac catalogues. The quality assessments are done from a visual inspection of QualityFITS outputs and from a series of statistics, tables and plots. An overview and a quick-look image quality assessments can be made using the QualityFITS web page. This “ID-card” for each image is produced automatically and is used to grade all images through the Youpi user interface 27 . The information returned by QualityFITS depends on the type of images (Multi-extension fits (MEF) or single extension FITS, the type of detectors (single CCD, mosaic of CCDs) and the origin of images. Depending on the steps of the processing (evaluation of input images or of final stacks), they are referenced as QualityFITS-in (or QFITS-in) or QualityFITS-out (or QFITS-out) products. As a general rule any CFHT images entering or leaving the Terapix center is passes through QualityFITSin or QualityFITS-out processing steps. 7042 CFHTLS input images and the 2276 T0007 output images were evaluated using this tool. The QualityFITS data products are images, tables and plots: • the FITS weight-map image, using WeightWatcher (Marmo & Bertin, 2008), in a multiple or single extension FITS format, like the input image; • the .ldac catalogue, using SExtractor; • an analysis of the shape and spatial variation of the PSF using PSFEX, sampled over the whole field (QualityFITS-out), or CCD by CCD for a mosaic (as for QualityFITS-in in the case of MegaCam input images); • an analysis of the sky background over the whole field of CCD by CCD for a mosaic; • an analysis of galaxy and stellar counts, based on an automatic blind star-galaxy separation from a r h 28 -magnitude diagram. The counts are shown on separate plots and compared to expectations: for the galaxies, they are compared to published results of CFHTLS Deep galaxy counts with the MegaCam filters; for stars, the counts are compared to Bahcall-Soneira models (Bahcall & Soneira, 1981); • an analysis of the astrometry of images, using SCAMP. For CFHT input images (QualityFITS-in), the astrometry analysis is approximate, and just relies on the FITS keywords. For CFHTLS stacks (QualityFITS-out), the analysis is based on a comparison between the CFHTLS and the 2MASS source catalogues; • a properly oriented (in case of reversed detector images due to flipped positions of output amplifiers), scaled and astrometrically calibrate binned view of each CCD and of the whole MegaCam field; 27 http://youpi.terapix.fr 28 half-light radius 98
• close up views of the central and the four corner regions of the MegaCam image. The views are unbinned 512×512 pixels JPEG sub-images of the five regions, but is sometimes expanded to 1024×1024 pixels when necessary; • a series of tables that contain information from the image FITS header, or statistics on the seeing, the background, the number of detections, either over the whole image or CCD by CCD for a mosaic. The QualityFITS output files are all public. The QualityFITS QA pages are available from the synoptic table. The T0007 synoptic table is a convenient way to have a quick look at the images. 99
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T0007 : The Final CFHTLS Release Pa
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patches are provided. Sources from
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Contents 1 CFHTLS-T0007 Executive S
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B.1 Rescaling factors applied to de
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33 Galaxy counts for the four Wide
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30 Description of parameters listed
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B A B A B A B A B A B A B A B A B A
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constraints. Two series of Deep sta
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evealed minor problems (such as unu
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een preferable because of the highe
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Figure 5: Outputs of the SCAMP cali
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Figure 7: CFHTLS T0007 absolute pho
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Figure 8: Seeing FWHM distribution
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Figure 10: Aperture correction (def
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Filter u g r i z - ApCorr - ApCorr
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Figure 14: Photometric calibration
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Figure 17: Photometric calibration
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Figure 18: Matching between one L99
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• four (u, g, r , i/y, z) Wide pa
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W1 W2 N N E E W3 W4 N N E E Figure
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CFHTLS Reference center Total Total
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Each tile is centered at a well-def
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Field Parameter u ∗ g r i y z W1
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Figure 23: Distribution of exposure
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Figure 25: Distribution of the medi
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All CFHTLS Wide images: (mean CCD s
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50% completeness are given for poin
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80% completeness limit (stars) 26.0
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10 5 W1 W2 W3 10 5 W1 W2 W3 N gal 0
Page 60 and 61: Wide Field Magnitude range u ∗ g
Page 62 and 63: Wide Field Magnitude range u ∗ g
Page 64 and 65: paths. From the joint effort betwee
Page 66 and 67: Wide field External magnitude offse
Page 68 and 69: Wide field External rms errors with
Page 70 and 71: Figure 38: Comparison of one CFHTLS
Page 72 and 73: 4.5.2 Absolute astrometric accuracy
Page 74 and 75: 4.6 Outliers, stacks with exception
Page 76 and 77: Figure 40: Mean RA-DEC offsets betw
Page 78 and 79: Figure 42: Mean RA-DEC offsets betw
Page 80 and 81: W Cartesian CFHTLS Special filter V
Page 82 and 83: accurately reflect the integration
Page 84 and 85: Field Parameter u ∗ g r i y z D1-
Page 86 and 87: Field Parameter u ∗ g r i y z D1-
Page 88 and 89: 76 Figure 43: Comparison of the (u
Page 90 and 91: Figure 44: Estimation of the intern
Page 92 and 93: 5.4 Depth and completeness limits T
Page 94 and 95: D2 u−band (25% best−seeing imag
Page 96 and 97: log Ngal 0.5 mag −1 deg −2 5 4
Page 98 and 99: - there is one chi2 image per Wide
Page 100 and 101: File name Content Data Size Number
Page 102 and 103: File name Content Data Size Number
Page 104 and 105: 6.3 Content of CFHTLS source catalo
Page 106 and 107: stacks made with the y-(i.MP9702) f
Page 108 and 109: Id Parameter Description Units Comm
Page 112 and 113: Figure 48: QFITS-out page of the W4
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Page 116 and 117: Figure 51: Upper panel: CFHTLS all-
Page 118 and 119: A CFHTLS T0007 Wide supplementary i
Page 120 and 121: Table 31 - Continued from previous
Page 122 and 123: A.2 List of images in each Wide sta
Page 138 and 139: DISTORT_GROUPS 1,1 # Polynom group
Page 140 and 141: #--------------------------- Photom
Page 142 and 143: #--------------------------- Photom
Page 144 and 145: #--------------------------- Photom
Page 146 and 147: #--------------------------- Backgr
Page 148 and 149: #--------------------------- Backgr
Page 150 and 151: #------------------------- Star/Gal
Page 152 and 153: #--------------------------- Star/G
Page 154 and 155: B.2 CFHTLS T0007 Deep configuration
Page 156 and 157: SCAMP astrometric run using interna
Page 158 and 159: SCAMP photometric run (D1,D2,D3,D4)
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B.2.2 SWarp stack configuration fil
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B.2.3 SWarp chi2-image configuratio
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B.2.4 SExtractor .ldac catalogue co
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B.2.5 SExtractor DUAL MODE .cat cat
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Acronyms & Abbreviations ASCII CADC
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References Astier, P., et al. 2006,
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