5.1 Overview

The CFHTLS Deep survey is composed of four independent MegaCam pointings in the D1, D2, D3 and D4 fields, whose sky location is shown in Figure 1, observed in all six MegaCam filters. It is composed of 96 u*,g,r,i,y and z stacks and 16 chi2 images (that is 112 images including the weight-maps). There are two types of stacks per Deep field: the “85%” best seeing images (hereafter the Dk-85 sample, k = 1 - 4) and the “25%” best seeing images (Dk-25). The two Dk series of stacks have exactly the same center positions.

The image selection criteria applied to the 10632 CFHTLS images for the production of the CFHTLS Deep survey has already been described in Section 3.4. Note that in addition to the CFHTLS images taken between May 26, 2003 and February 02, 2009 on the D2-u* field contains MegaCam images taken by the COSMOS consortium (?).

The T0007 CFHTLS Deep survey contains in total 8916 images. After proper selection, the remaining 8638 images were combined into stacks as follows: 634 u*, 1457 g, 1932 r, 1990 i, 691 y and 1934 z.







Field name
Reference center
Comment
RA DEC
(J2000) (J2000)





D1 02:25:59.00 -04:29:40
D2 10:00:28.00 +02:12:30 COSMOS u* data included
D3 14:19:27.00 +52:40:56
D4 22:15:31.00 -17:43:56






Table 16: Location of the CFHTLS Deep fields. All fields cover 1 deg2 and are taken in all six filters.

All stacks have the same pixel scale and cover exactly 1×1 deg2 (19354×19354 pixels of 0.1860"). For all fields with the exception of D2-u* the stacks are only composed of images that are part of a CFHTLS Deep observing sequence and that are within a radius of 3 arc-minutes with respect to the CFHTLS Deep center fields. For the D2-u*, we included all u*-COSMOS images that passed the selection, without restriction on the radial distance.

The Deep stacks combine sets of images obtained during sequences of medium exposures (few hundreds of seconds). Each exposure is followed by a small shift of the telescope to fill the physical gaps between CCDs. The shifts are within a box of 4 in DEC and 3 arcminutes in RA. The D2-u* stacks COSMOS data are shifted by 30 arcminutes in both RA and DEC directions in order to pave the 1.4×1.4 deg2 of the cosmos survey. These images are combined with CFHTLS D2-u* observations and cut to provide the 1×1 deg2 centered on the CFHTLS D2.

The center position of each stack is predefined. The coordinates of a stack center position are given in Table 16, and are exactly the same for all filters. D1, D2, D3 and D4 are therefore composed of a complete set of u*,g,r,i,y and z images of 1 deg2 each.

Tables 17 and 18 summarize the properties of Deep median-combined stacks; the characteristics of the sigma-combined stacks are given in Tables19 and 20. (Note that the exposure time u*-band does not accurately reflect the integration time per pixel because most COSMOS images are shifted by 30 and only fill one quadrant of the CFHTLS u*-band stack. The D2-u* corresponds to the innermost regions of Fig. 46, delimited by the black contours. Table 22 describes each sub-field in more detail).










Field Parameter u* g r i y z








D1-25 Nb images 29 96 134 138 37 142
Exp. time [s] 19142 23106 42429 66490 13961 51129
Seeing ["] 0.72 0.66 0.62 0.62 0.52 0.56
80% Compl. (stellar) 26.24 0.10 26.31 0.10 25.92 0.10 25.43 0.10 25.39 0.10 25.11 0.10
80% Compl. (extended) 25.43 0.10 25.48 0.10 24.94 0.10 24.57 0.10 24.32 0.10 23.98 0.10
Int. astrom. err. (0.042",0.042") (0.049",0.048") (0.048",0.048") (0.047",0.047") (0.041",0.040") (0.050",0.050")
Ext. astrom. err. (0.25",0.23") (0.26",0.25") (0.25",0.24") (0.25",0.24") (0.27",0.25") (0.26",0.24")
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
D2-25 Nb images 128 83 114 107 60 104
Exp. time [s] ~25000 18680 34208 51808 24483 37446
Seeing ["] 0.75 0.64 0.58 0.57 0.57 0.56
80% Compl. (stellar) 26.26 0.10 26.31 0.10 25.91 0.10 25.51 0.10 25.65 0.10 25.14 0.10
80% Compl. (extended) 25.55 0.10 25.42 0.10 24.93 0.10 24.63 0.10 24.55 0.10 24.07 0.10
Int. astrom. err. (0.070",0.068") (0.068",0.065") (0.065",0.063") (0.062",0.060") (0.054",0.052") (0.024",0.024")
Ext. astrom. err. (0.21",0.21") (0.23",0.22") (0.22",0.22") (0.22",0.22") (0.23",0.22") (0.21",0.22")
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
cfhtls-sdss δm[mag.] -0.051 -0.005 +0.010 +0.003 -0.004 +0.009
D3-25 Nb images 29 96 134 138 37 142
Exp. time [s] 19806 20717 36623 64425 19209 45023
Seeing ["] 0.75 0.67 0.63 0.61 0.61 0.54
80% Compl. (stellar) 26.12 0.10 26.29 0.10 25.76 0.10 25.48 0.10 25.42 0.10 25.07 0.10
80% Compl. (extended) 25.30 0.10 25.44 0.10 24.90 0.10 24.58 0.10 24.46 0.10 23.94 0.10
Int. astrom. err. (0.060",0.058") (0.065",0.064") (0.065",0.064") (0.064",0.063") (0.054",0.053") (0.075",0.074")
Ext. astrom. err. (0.23",0.23") (0.25",0.25") (0.25",0.25") (0.25",0.25") (0.26",0.25") (0.25",0.25")
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.04
cfhtls-sdss δm[mag.] -0.042 -0.002 +0.014 +0.003 -0.001 -0.004
D4-25 Nb images 31 96 118 123 29 120
Exp. time [s] 20462 23345 39066 57088 11561 43207
Seeing ["] 0.74 0.70 0.60 0.57 0.57 0.55
80% Compl. (stellar) 26.01 0.10 26.14 0.10 25.76 0.10 25.42 0.10 25.45 0.10 25.06 0.10
80% Compl. (extended) 25.22 0.10 25.33 0.10 24.93 0.10 24.60 0.10 24.28 0.10 23.87 0.10
Int. astrom. err. (0.053",0.054") (0.063",0.062") (0.061",0.060") (0.060",0.060") (0.046",0.054") (0.067",0.066")
Ext. astrom. err. (0.22",0.21") (0.23",0.23") (0.23",0.22") (0.22",0.22") (0.24",0.23") (0.23",0.22")
Mag. int. err. [mag.] 0.04 0.02 0.02 0.02 0.02 0.03









Table 17: Summary of the “25%” best=seeing stack parameters. “80% Compl.” is the 80% completeness limit. The seeing is the median fwhm. Astrometric errors are given along the two (x,y)=(ns,ew) axes. The internal astrometric errors are derived from SCAMP calibrations, and the external errors are QualityFITS-out outputs, from the comparison of source positions on each stack with the 2MASS astrometric positions. The "Mag. int. err." are the mean internal photometric errors from the mean of the three magnitude ranges of Table 21. The δmmagnitude is the mean magnitude offset between CFHTLS-T0007 and the SDSS-DR8 survey, averaged over a Deep field.










Field Parameter u* g r i y z








D1-85 Nb images 113 382 528 551 148 553
Exp. time [s] 74590 89334 171876 264804 61768 199116
Seeing ["] 0.87 0.83 0.77 0.76 0.71 0.72
80% Compl. (stellar) 26.44 0.10 26.07 0.10 25.61 0.10 25.33 0.10 25.38 0.10 24.99 0.10
80% Compl. (extended) 25.72 0.10 25.33 0.10 24.75 0.10 24.40 0.10 24.48 0.10 24.16 0.10
Int. astrom. err. (0.042",0.042") (0.049",0.048") (0.048",0.048") (0.047",0.047") (0.041",0.040") (0.050",0.050")
Ext. astrom. err. (0.26",0.23") (0.26",0.25") (0.26",0.24") (0.25",0.24") (0.26",0.25") (0.25",0.23")
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
D2-85 Nb images 282 332 449 422 235 410
Exp. time [s] ~45000 74723 135875 199655 99176 147628
Seeing ["] 0.84 0.80 0.75 0.72 0.69 0.68
80% Compl. (stellar) 26.42 0.10 26.08 0.10 25.66 0.10 25.30 0.10 25.51 0.10 25.01 0.10
80% Compl. (extended) 25.77 0.10 25.33 0.10 24.74 0.10 24.49 0.10 24.54 0.10 24.15 0.10
Int. astrom. err. (0.070",0.068") (0.068",0.065") (0.065",0.063") (0.062",0.060") (0.054",0.052") (0.024",0.024")
Ext. astrom. err. (0.21",0.22") (0.22",0.22") (0.22",0.22") (0.22",0.22") (0.23",0.23") (0.21",0.22")
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
cfhtls-sdss δm[mag.] -0.056 -0.006 +0.011 +0.007 -0.008 -0.011
D3-85 Nb images 118 361 483 527 192 500
Exp. time [s] 77904 80977 146374 249016 82276 180097
Seeing ["] 0.88 0.85 0.78 0.76 0.78 0.69
80% Compl. (stellar) 26.26 0.10 26.11 0.10 25.58 0.10 25.32 0.10 25.54 0.10 25.03 0.10
80% Compl. (extended) 25.63 0.10 25.29 0.10 24.69 0.10 24.39 0.10 24.46 0.10 24.13 0.10
Int. astrom. err. (0.060",0.058") (0.065",0.064") (0.065",0.064") (0.064",0.063") (0.054",0.053") (0.075",0.074")
Ext. astrom. err. (0.24",0.24") (0.25",0.25") (0.25",0.25") (0.24",0.25") (0.26",0.26") (0.25",0.25")
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.04
cfhtls-sdss δm[mag.] -0.042 -0.004 +0.016 +0.001 -0.003 -0.004
D4-85 Nb images 121 382 472 490 116 471
Exp. time [s] 77269 89541 155609 235153 45767 169588
Seeing ["] 0.89 0.82 0.73 0.69 0.69 0.66
80% Compl. (stellar) 26.14 0.10 25.99 0.10 25.61 0.10 25.35 0.10 25.40 0.10 25.09 0.10
80% Compl. (extended) 25.53 0.10 25.34 0.10 24.85 0.10 24.49 0.10 24.45 0.10 24.17 0.10
Int. astrom. err. (0.053",0.054") (0.063",0.062") (0.061",0.060") (0.060",0.060") (0.046",0.054") (0.067",0.066")
Ext. astrom. err. (0.22",0.22") (0.23",0.23") (0.23",0.22") (0.22",0.22") (0.24",0.23") (0.22",0.22")
Mag. int. err. [mag.] 0.04 0.02 0.02 0.02 0.02 0.03









Table 18: Summary of the “85%” Deep stack parameters. "80% Compl." is the 80% completeness limit. The seeing is the median fwhm. Astrometric errors are given along the two (x,y)=(ns,ew) axes. The internal photometric errors are from the SCAMP calibrations, and the external errors are QualityFITS-out outputs, from the comparison of source positions on each stack with the 2MASS astrometric positions. The "Mag. int. err." are the mean internal photometric errors from the mean of the three magnitude ranges of Table 21. The δmmagnitude is the mean magnitude offset between CFHTLS-T0007 and the SDSS-DR8 survey, averaged over a Deep field.










Field Parameter u* g r i y z








D1-25 Seeing ["] 0.71 0.67 0.63 0.61 0.54 0.56
80% Compl. (stellar) 26.43 0.10 26.36 0.10 25.86 0.10 25.55 0.10 25.43 0.10 25.23 0.10
80% Compl. (extended) 25.61 0.10 25.54 0.10 24.95 0.10 24.63 0.10 24.41 0.10 24.14 0.10
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
D2-25 Seeing ["] 0.76 0.64 0.60 0.58 0.58 0.55
80% Compl. (stellar) 26.43 0.10 26.34 0.10 25.94 0.10 25.59 0.10 25.44 0.10 25.22 0.10
80% Compl. (extended) 25.74 0.10 25.51 0.10 24.99 0.10 24.60 0.10 24.58 0.10 24.21 0.10
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
cfhtls-sdss δm[mag.] -0.057 -0.005 +0.011 +0.004 -0.009 +0.010
D3-25 Seeing ["] 0.76 0.68 0.65 0.62 0.62 0.53
80% Compl. (stellar) 26.24 0.10 26.34 0.10 25.84 0.10 25.49 0.10 25.46 0.10 25.14 0.10
80% Compl. (extended) 25.49 0.10 25.47 0.10 24.97 0.10 24.64 0.10 24.56 0.10 24.11 0.10
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.04
cfhtls-sdss δm[mag.] -0.041 +0.004 +0.015 +0.007 -0.012 -0.001
D4-25 Seeing ["] 0.72 0.68 0.60 0.56 0.56 0.54
80% Compl. (stellar) 26.28 0.10 26.27 0.10 25.86 0.10 25.51 0.10 25.50 0.10 25.20 0.10
80% Compl. (extended) 25.49 0.10 25.43 0.10 25.00 0.10 24.69 0.10 24.43 0.10 24.03 0.10
Mag. int. err. [mag.] 0.04 0.02 0.02 0.02 0.02 0.03









Table 19: Characteristics of the “25%” best-seeing sigma-combined stacks. "80% Compl." is the 80% completeness limit. The seeing is the median fwhm. Astrometric errors are given along the two (x,y)=(ns,ew) axes. The "Mag. int. err." are the mean internal photometric errors from the mean of the three magnitude ranges of Table 21. The δmmagnitude is the mean magnitude offset between CFHTLS-T0007 and the SDSS-DR8 survey, averaged over a Deep field.










Field Parameter u* g r i y z








D1-85 Seeing ["] 0.84 0.81 0.77 0.74 0.71 0.72
80% Compl. (stellar) 26.51 0.10 25.98 0.10 25.62 0.10 25.32 0.10 25.47 0.10 24.98 0.10
80% Compl. (extended) 25.87 0.10 25.32 0.10 24.71 0.10 24.37 0.10 24.54 0.10 24.22 0.10
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
D2-85 Seeing ["] 0.82 0.78 0.74 0.72 0.70 0.66
80% Compl. (stellar) 26.56 0.10 26.05 0.10 25.56 0.10 25.22 0.10 25.48 0.10 25.15 0.10
80% Compl. (extended) 25.95 0.10 25.32 0.10 24.72 0.10 24.46 0.10 24.55 0.10 24.28 0.10
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.03
cfhtls-sdss δm[mag.] -0.057 -0.004 +0.011 +0.002 -0.011 +0.010
D3-85 Seeing ["] 0.87 0.84 0.78 0.75 0.77 0.69
80% Compl. (stellar) 26.51 0.10 26.06 0.10 25.54 0.10 25.20 0.10 25.51 0.10 25.14 0.10
80% Compl. (extended) 25.86 0.10 25.26 0.10 24.66 0.10 24.35 0.10 24.46 0.10 24.20 0.10
Mag. int. err. [mag.] 0.03 0.02 0.02 0.02 0.02 0.04
cfhtls-sdss δm[mag.] -0.040 +0.005 +0.016 +0.000 -0.012 -0.004
D4-85 Seeing ["] 0.86 0.81 0.72 0.69 0.66 0.65
80% Compl. (stellar) 26.44 0.10 25.95 0.10 25.53 0.10 25.31 0.10 25.53 0.10 25.16 0.10
80% Compl. (extended) 25.79 0.10 25.32 0.10 24.82 0.10 24.48 0.10 24.47 0.10 24.26 0.10
Mag. int. err. [mag.] 0.04 0.02 0.02 0.02 0.02 0.03









Table 20: Characteristics of the “85%” best-seeing sigma-combined stack parameters.