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Wide Field Magnitude range u ∗ g r i y z
[MegaCam AB] [mag.] [mag.] [mag.] [mag.] [mag.] [mag.]
W1 [19.0 − 20.0] 0.002 0.002 0.003 0.006 0.003 0.008
[20.0 − 21.0] 0.005 0.003 0.010 0.007 0.007 0.017
[21.0 − 22.0] 0.008 0.009 0.011 0.016 0.014 0.043
[22.0 − 23.0] 0.020 0.015 0.025 0.037 0.035 0.098
[23.0 − 24.0] 0.046 0.035 0.061 0.089 0.083 0.159
W2 [19.0 − 20.0] 0.002 0.002 0.003 0.003 - 0.009
[20.0 − 21.0] 0.004 0.004 0.005 0.007 - 0.018
[21.0 − 22.0] 0.009 0.009 0.012 0.016 - 0.041
[22.0 − 23.0] 0.020 0.016 0.027 0.038 - 0.097
[23.0 − 24.0] 0.050 0.038 0.067 0.087 - 0.161
W3 [19.0 − 20.0] 0.002 0.001 0.002 0.003 0.002 0.008
[20.0 − 21.0] 0.004 0.003 0.005 0.007 0.007 0.018
[21.0 − 22.0] 0.008 0.007 0.011 0.017 0.015 0.040
[22.0 − 23.0] 0.020 0.015 0.025 0.039 0.034 0.095
[23.0 − 24.0] 0.049 0.035 0.060 0.094 0.084 0.140
W4 [19.0 − 20.0] 0.002 0.001 0.002 0.003 0.003 0.009
[20.0 − 21.0] 0.004 0.003 0.005 0.007 0.007 0.019
[21.0 − 22.0] 0.008 0.007 0.013 0.017 0.015 0.044
[22.0 − 23.0] 0.020 0.015 0.028 0.041 0.035 0.098
[23.0 − 24.0] 0.049 0.035 0.057 0.094 0.088 0.142
Table 8: Internal photometric errors per magnitude bins derived for each CFHTLS Wide field. The simulated
sources include only stars and are detected and analyzed in the same was as real sources. The errors are the
FWHM/2.35, as shown in Fig. 34. They are corrected from the amplitude of the tilt from horizontal of the difference
between of the input and output magnitudes as function of magnitude inside the bin. The magnitude ranges quoted
in the table only comprise bins with all sources below the completeness limits and with all sources having a signalto-noise
ratio larger than 10. The W2 y-band is not quoted because it only concerns two stacks and the statistics
are meaningless for these fields.
4.4.2 Error estimation from overlapping Wide tiles
An estimation of the internal photometric errors of the Wide survey can also be made using common
sources in overlapping tiles. Since each tile is shifted by 56 ′ in RA and 57 ′ in DEC with respect to its
nearest tiles overlap regions are stripes of 4 ′ × 60 ′ or 3 ′ × 60 ′ (see Fig. 21). We use the u ∗ , g, r, i and
z-band MAG_IQ20 stars located in these regions to compare the photometry of sources detected in two
adjacent stacks. The analysis is restricted to stars to avoid the specific issues involved in the use of
MAG_AUTO for galaxies. Furthermore, it can only be applied on thin strips located at the edges of images
where sources have lower signal-to-noise due to the adopted dithering strategy; therefore, this analysis
should be regarded as secondary to our previous simulation-based estimations.
The first estimate of internal errors is derived by calculating for each pair of overlapping tiles the median
of the magnitude differences of all source pairs in the overlapping regions. This value is the field to field
photometric offset between the two contiguous tiles. For a complete Wide patch, the standard deviation
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