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.
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| | | | | Field name | Reference center | Comment |
| RA | DEC | | | (J2000) | (J2000) | |
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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 | |
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Table 16: | Location of the CFHTLS Deep fields. All fields cover 1 deg2 and are taken in all six filters. |
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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).
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| Field | Parameter | u* | g | r | i | y | z |
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| 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 |
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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 |
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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 |
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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 ⟨δm⟩ magnitude is the mean magnitude offset between
CFHTLS-T0007 and the SDSS-DR8 survey, averaged over a Deep field. |
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| Field | Parameter | u* | g | r | i | y | z |
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| 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 |
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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 |
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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 |
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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 ⟨δm⟩ magnitude is the mean magnitude offset between CFHTLS-T0007 and the
SDSS-DR8 survey, averaged over a Deep field. |
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| Field | Parameter | u* | g | r | i | y | z |
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| 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 |
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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 |
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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 |
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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 ⟨δm⟩ magnitude is the mean magnitude offset between
CFHTLS-T0007 and the SDSS-DR8 survey, averaged over a Deep field. |
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| Field | Parameter | u* | g | r | i | y | z |
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| 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 |
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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 |
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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 |
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Table 20: | Characteristics of the “85%” best-seeing sigma-combined stack parameters. |
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