Terapix Star Formation Region IC 1396, © 2002 CFHT
CFHTLS / SDSS comparisons
by HJMCC HJMCC - Updated November 22nd, 2008

The photometric calibration of the CFHTLS/WIDE survey of the T0005 release has been inspected using the SDSS data (http://www.sdss.org). For each CFHTLS WIDE field, the equivalent SDSS field has been identified. Then the photometry has been compared using common bright stars. Only stellar objects with i' < 21 (i.e the limiting magnitude for the star/galaxy separation) and a cross-identification radius of 2'' has been used. For our analysis only stars with 17 < i'< 21 were used and stars inside a masked region were avoided.

This table lists the weighted mean offset derived for each CFHTLS stack that have common areas with the SDSS. The mean offset is obtained by comparing CFHTLS and SDSS magnitudes of photometric standard stars common to both samples. In additon, the intrinsic photometric erros (CFHTLS and SDSS) were included in the calculation of the offsets. The comparison is done after CFHTLS magnitudes have been transformed into the SDSS system (see Regnault et al. and the previous web page). The values in bold are the CFHTLS-SDSS differences for the new i-filter (i.9702) for which a specific transformation different from the i.9701 has been applied (see the T0005 explanatory document for more details) . The typical errors in the determination of the offsets is +/- 0.025 mag in each filter.

The W2 field as well as D1 and D4 do not overlap with SDSS.

Maps of these offsets on the sky for each Wide field are given at the bottom of this page

W1 offset-uoffset-goffset-roffset-ioffset-z
W1_ugriz_020241-075600 -- 0.06 0.01 0.04 --
W1_ugriz_020241-085200 -- 0.07 0.01 0.04 --
W1_ugriz_020241-094800 -- 0.02 0.01 0.04 --
W1_ugriz_020241-104400 -- -0.05 -0.030.01 --
W1_ugriz_020631-075600 -- 0.07 0.01 0.05 --
W1_ugriz_020631-085200 -- 0.03 0.02 0.04 --
W1_ugriz_020631-094800 -- -0.01 -0.02 0.03 --
W1_ugriz_021021-075600 -0.01 0.01 0.04 0.06 0.06
W1_ugriz_021021-085200 0.01 0.03 0.02 0.06 0.06
W1_ugriz_021021-094800 0.01 0.01 -0.01 0.04 0.11
W1_ugriz_021410-075600 -0.05 -0.02 0.05 0.04 0.03
W1_ugriz_021410-085200 0.01 0.01 -0.04 0.05 0.04
W1_ugriz_021410-094800 0.01 0.03 -0.02 0.01 0.11
W1_ugriz_021800-070000 -0.04 -0.06 -0.04 0.03 -0.02
W1_ugriz_021800-075600 -0.02 0.02 0.01 0.05 0.05
W1_ugriz_021800-085200 0.05 -0.010.02 0.03 -0.01
W1_ugriz_021800-094800 0.05 0.02 -0.03 0.04 0.08
W1_ugriz_022150-070000 0.01 -0.02 -0.02 0.06 0.04
W1_ugriz_022150-075600 0.14 0.02 0.01 0.06 0.02
W1_ugriz_022150-085200 0.02 0.02 -0.01 0.03 -0.01
W1_ugriz_022150-094800 -0.05 0.01 0.01 0.02 0.10
W1_ugriz_022539-070000 0.08 0.04 -0.01 0.06 0.03
W1_ugriz_022539-075600 0.02 0.01 -0.01 0.03 0.02
W1_ugriz_022539-085200 -0.03 0.01 -0.01 0.03 0.02
W1_ugriz_022539-094800 0.03 0.01 0.01 0.02 0.10
W1_ugriz_022929-070000 0.06 0.05 -0.01 0.02 0.04
W1_ugriz_022929-075600 0.03 0.01 -0.01 0.03 -0.03
W1_ugriz_022929-085200 -0.01 0.03 0.01 0.02 0.01
W1_ugriz_022929-094800 -0.01 0.01 0.02 -0.01 0.07
W1_ugriz_023319-070000 0.04 0.06 -0.1 0.01 0.02
W1_ugriz_023319-075600 0.02 0.01 -0.01 0.02 0.01
W1_ugriz_023319-085200 -0.07 0.02 -0.01 0.01 0.01
W1_ugriz_023319-094800 0.01 -0.01 -0.01 -0.01 0.02

W3 offset-uoffset-goffset-roffset-ioffset-z
W3_ugriz_135752+571831 -- 0.03 0.02 0.01 0.07
W3_ugriz_135820+562231 0.14 0.02 0.03 0.01 -0.02
W3_ugriz_135846+552631 0.06 0.01 0.01 0.04 -0.04
W3_ugriz_135910+543031 0.05 0.02 0.01 0.03 0.02
W3_ugriz_135933+533431 0.11 0.01 -0.01 0.01 -0.02
W3_ugriz_135955+523831 0.06 0.01 0.05 0.02 -0.01
W3_ugriz_140016+514231 0.01 0.01 0.04 0.01 -0.01
W3_ugriz_140433+571831 -- 0.02 -0.02 0.03 0.05
W3_ugriz_140451+562231 0.13 -0.01 0.01 0.02 0.02
W3_ugriz_140509+552631 0.08 0.01 0.02 0.02 -0.03
W3_ugriz_140525+543031 0.08 0.02 -0.01 0.05 -0.03
W3_ugriz_140540+533431 0.08 0.04 -0.02 0.02 -0.03
W3_ugriz_140555+523831 0.05 0.02 0.01 0.02 -0.02
W3_ugriz_140609+514231 0.10 0.02 0.01 0.02 0.01
W3_ugriz_141113+571831 -- 0.03 -0.02 0.04 0.04
W3_ugriz_141123+562231 0.1 0.01 0.02 0.03 -0.02
W3_ugriz_141131+552631 0.07 0.01 0.01 0.02 -0.02
W3_ugriz_141139+543031 0.13 0.04 -0.01 0.02 0.04
W3_ugriz_141147+533431 0.11 0.01 0.01 0.03 0.02
W3_ugriz_141155+523831 0.09 0.03 0.01 0.02 -0.03
W3_ugriz_141202+514231 0.03 0.01 0.04 0.01 -0.03
W3_ugriz_141754+514231 0.06 0.01 -0.01 0.02 -0.01
W3_ugriz_141754+523831 0.09 0.01 -0.01 0.02 -0.01
W3_ugriz_141754+533431 0.06 0.03 -0.010.01 0.01
W3_ugriz_141754+543031 0.07 0.02 -0.02 -0.01 -0.03
W3_ugriz_141754+552631 0.10 0.02 0.01 0.01 -0.02
W3_ugriz_141754+562231 0.09 -0.01 -0.02 0.03 0.01
W3_ugriz_141754+571831 -- 0.03 -0.02 0.03 0.11
W3_ugriz_142347+514231 0.15 0.01 0.01 0.01 -0.03
W3_ugriz_142354+523831 0.13 0.01 0.01 0.01 -0.01
W3_ugriz_142401+533431 0.11 0.02 0.01 0.01 -0.01
W3_ugriz_142409+543031 0.05 0.02 -0.01 0.01 -0.01
W3_ugriz_142417+552631 0.06 0.01 0.01 0.01 -0.01
W3_ugriz_142425+562231 0.05 0.01 -0.01 0.02 0.01
W3_ugriz_142435+571831 -- 0.02 -0.01 0.01 0.08
W3_ugriz_142939+514231 -- 0.03 -0.02 0.01 -0.03
W3_ugriz_142953+523831 -- 0.02 0.01 0.02 0.01
W3_ugriz_143008+533431 -- 0.01 0.01 0.01 -0.03
W3_ugriz_143023+543031 -- 0.01 0.01 0.02 -0.04
W3_ugriz_143040+552631 -- 0.01 -0.01 0.02 -0.02
W3_ugriz_143057+562231 -- 0.01 0.01 0.01 -0.01
W3_ugriz_143115+571831 -- -0.01 -0.02 0.01 0.08
W3_ugriz_143532+514231 -- 0.01 -0.03 0.02 -0.02
W3_ugriz_143553+523831 -- 0.01 -0.020.01 -0.02
W3_ugriz_143615+533431 -- 0.03 -0.04 -0.01 -0.04
W3_ugriz_143638+543031 -- 0.04 -0.03 -0.01 -0.03
W3_ugriz_143702+552631 -- 0.01 -0.04 0.01 -0.03
W3_ugriz_143728+562231 -- 0.02 -0.03 0.01 -0.01
W3_ugriz_143756+571831 -- 0.01 -0.03 0.02 0.06

W4 offset-uoffset-goffset-roffset-ioffset-z
W4_ugriz_220154+011900 0.09 0.02 0.01 0.04 -0.01
W4_ugriz_220154-003100 0.08 -0.01 0.01 0.02 -0.01
W4_ugriz_220542+011900 0.10 0.01 -0.02 0.01 -0.03
W4_ugriz_220930+002300 0.03 0.04 -0.01 0.01 -0.03
W4_ugriz_220930+011900 0.03 0.02 -0.01 -0.01 -0.01
W4_ugriz_220930-003100 0.03 0.01 -0.01 0.03 -0.03
W4_ugriz_221318+002300 0.05 0.02 -0.01 0.01 -0.03
W4_ugriz_221318+011900 0.09 0.02 -0.03 0.03 -0.01
W4_ugriz_221318-003100 0.04 0.03 -0.01 0.02 -0.01
W4_ugriz_221706+002300 0.06 0.04 -0.03 0.02 -0.02
W4_ugriz_221706+011900 0.08 0.02 0.04 -0.01 -0.03
W4_ugriz_221706-003100 0.03 0.02 -0.01 0.02 -0.03
W4_ugriz_222054+002300 0.09 0.01 0.01 -0.01 -0.01
W4_ugriz_222054+011900 0.09 0.01 -0.01 0.01 -0.01

D2 offset-uoffset-goffset-roffset-ioffset-z
CFHTLS_D25_ugriz_100028+021230 -0.03 0.03 0.01 0.01 0.01
CFHTLS_D85_ugriz_100028+021230 0.03 0.01 0.01 0.01 0.03

D3 offset-uoffset-goffset-roffset-ioffset-z
CFHTLS_D25_ugriz_141927+524056 0.03 0.03 0.01 0.04 -0.01
CFHTLS_D85_ugriz_141927+524056 0.02 0.03 0.01 0.05 -0.01

Overview per wide field and per filter: Offset map for W1 Offset map for W3 Offset map for W4 :

Amplitude of (CFHTLS-SDSS) offsets as function of position on each Wide field. Each colored square is a CFHTLS Wide stack. It covers one Megacam field. The color is the amplitude. From left to right and top to bottom: u, g, r, i, z. Data are missing when stacks are not available or when there are no stars in common between the stack and SDSS.

Back to T0005 summary page


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