Terapix Star Formation Region IC 1396, © 2002 CFHT
Table of offsets between ZP(CFHT) and ZP(SDSS)
by YME YME - Updated September 25th, 2008

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This table lists the 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. The comparison is done after CFHTLS magnitudes have been transformed into the SDSS system (see Regnault et al. and the previous web page). There are however only a few stacks that have common stars with SDSS. The W2 field does has no overlap with SDSS.

Note that there s a large offset in some u-band data (0.20). It only concerns data obtained after Februray 2006 and is related to a CFHT u-band calibration problem. The 0.2 mag. offset in u-band applies to ALL u-data obtained since March 2006. In particular all W4-u band must be corrected. Before March 2006, no offset correction is needed. For the u-band data sets we do not have SDSS comparison, we therefore recommend to apply an 0.20 mag. offset to stacks done with images having Obs. Date after February 2006. The u-band image observation dates used for all u-band stacks are given in the last column of the T0004 quick summary table

Maps of these offsets on the sky are given at the bottom of this page.

W1 offset-uoffset-goffset-roffset-ioffset-z
W1_ugriz_021021-075600 -- 0.03 0.03 0.01 --
W1_ugriz_021021-085200 -- 0.03 0.01 0.05 --
W1_ugriz_021410-075600 -- -0.01 0.01 0.05 --
W1_ugriz_021410-085200 -- -0.01 -0.01 0.05 --
W1_ugriz_0218000-08520 -- -0.01 -0.01 0.03 --
W1_ugriz_021800-070000 -- -0.03 -0.03 0.03 --
W1_ugriz_021800-075600 -- -0.01 -0.01 0.01 --
W1_ugriz_021800-094800 -- 0.01 -0.01 0.03 --
W1_ugriz_0221500-07560 -- -0.01 -0.01 0.01 --
W1_ugriz_022150-070000 -- -0.01 -0.03 0.05 0.03
W1_ugriz_022150-085200 -- 0.01 -0.03 0.03 --
W1_ugriz_022539-070000 -- 0.03 -0.01 0.05 --
W1_ugriz_022539-075600 -- -0.01 -0.01 0.03 --
W1_ugriz_022539-085200 -- 0.01 -0.01 0.01 --
W1_ugriz_022929-070000 0.01 0.05 -0.01 0.01 -0.01
W1_ugriz_022929-075600 -- -0.01 -0.01 0.03 --
W1_ugriz_022929-085200 -- 0.01 0.01 0.01 --
W1_ugriz_023319-070000 0.03 0.03 -0.01 -0.01 0.01
W1_ugriz_023319-075600 -- -0.01 -0.01 0.01 --
W1_ugriz_023319-085200 -- 0.01 -0.01 0.01 --
W1_ugriz_023319-094800 -- -0.01 0.01 -0.01 --

W3 offset-uoffset-goffset-roffset-ioffset-z
W3_ugriz_135752+571831 -- 0.01 0.03 0.01 --
W3_ugriz_135820+562331 -- 0.01 0.05 0.03 --
W3_ugriz_135846+552631 -- 0.01 0.03 0.05 --
W3_ugriz_135910+543031 -- 0.01 0.03 0.01 -0.03
W3_ugriz_135933+533431 -- 0.01 -0.03 0.01 -0.05
W3_ugriz_140433+571831 -- 0.01 -0.01 0.06 --
W3_ugriz_140525+543031 -- 0.01 -0.01 0.05 -0.05
W3_ugriz_140540+533431 -- 0.03 -0.03 0.01 -0.05
W3_ugriz_140609+514231 -- 0.03 0.01 0.01 0.01
W3_ugriz_141113+571831 -- 0.01 -0.03 0.05 --
W3_ugriz_141123+562231 -- 0.01 0.03 0.03 --
W3_ugriz_141131+552631 -- 0.01 0.01 0.03 --
W3_ugriz_141139+543031 -- 0.05 -0.01 0.01 -0.05
W3_ugriz_141147+533431 -- 0.01 -0.03 0.03 0.01
W3_ugriz_141754+514231 -- 0.01 0.01 0.03 --
W3_ugriz_141754+523831 -- 0.01 -0.01 0.01 --
W3_ugriz_141754+543031 -- 0.03 -0.01 -0.01 -0.07
W3_ugriz_141754+552631 -- 0.03 0.01 0.01 --
W3_ugriz_141754+562231 -- 0.01 -0.03 0.03 --
W3_ugriz_141754+571831 -- 0.03 -0.01 0.03 --
W3_ugriz_142347+514231 -- -0.01 -0.01 0.01 --
W3_ugriz_142354+523831 -- 0.01 0.01 0.01 --
W3_ugriz_142401+533431 -- 0.03 0.01 0.01 --
W3_ugriz_142409+543031 -- 0.03 0.01 0.01 --
W3_ugriz_142417+552631 -- 0.01 0.01 0.01 --
W3_ugriz_142425+562231 -- 0.01 -0.01 0.03 --
W3_ugriz_142435+571831 -- 0.01 -0.01 0.01 --
W3_ugriz_142939+514231 -- 0.03 -0.03 -0.01 --
W3_ugriz_142953+523831 -- 0.03 0.01 0.01 --
W3_ugriz_143008+533431 -- 0.03 0.01 -0.01 --
W3_ugriz_143023+543031 -- 0.01 0.01 0.01 --
W3_ugriz_143040+552631 -- 0.01 -0.01 0.01 --
W3_ugriz_143115+571831 -- -0.01 -0.01 0.03 --
W3_ugriz_143532+514231 -- 0.01 -0.03 0.03 --
W3_ugriz_143553+523831 -- 0.01 -0.01 0.01 --
W3_ugriz_135955+523831 0.21 0.01 0.03 0.01 -0.03
W3_ugriz_140016+514231 0.21 0.03 0.03 -0.01 -0.03
W3_ugriz_140555+523831 0.25 0.03 -0.01 0.01 -0.05
W3_ugriz_141154+523831 0.31 0.03 -0.03 0.03 -0.05
W3_ugriz_140508+552631 -- 0.01 0.01 0.03 --
W3_ugriz_141201+514231 0.25 0.01 0.03 0.01 -0.05
W3_ugriz_135820+562331 -- 0.01 0.05 0.03 --

W4 offset-uoffset-goffset-roffset-ioffset-z
W4_ugriz_220542+011900 -- 0.01 -0.01 0.01 --
W4_ugriz_220930+002300 0.21 0.05 0.01 0.01 -0.05
W4_ugriz_220930-003100 0.19 0.01 -0.03 0.03 -0.03
W4_ugriz_220930+011900 -- 0.03 0.01 -0.01 --
W4_ugriz_221318-002300 0.25 0.01 0.01 -0.01 -0.03
W4_ugriz_221318-003100 0.21 0.01 -0.01 0.01 -0.03
W4_ugriz_221318+011900 0.23 0.03 -0.03 0.01 -0.01
W4_ugriz_221706+002300 0.21 0.03 -0.03 0.01 -0.03
W4_ugriz_221706+011900 0.23 0.01 0.05 -0.01 -0.05
W4_ugriz_222054+002300 0.21 0.01 0.01 -0.01 -0.03
W4_ugriz_222054-003100 0.17 -0.01 0.01 0.01 -0.03
W4_ugriz_222054+011900 0.25 -0.01 0.01 0.01 -0.03

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 0.05 0.01 0.01 0.01 -0.01

D3 offset-uoffset-goffset-roffset-ioffset-z
CFHTLS_D25_ugriz_141927+524056 0.09 0.03 0.01 0.01 -0.03
CFHTLS_D85_ugriz_141927+524056 0.19 0.03 0.01 0.01 -0.05

Overview per wide field and per filter: Offset maps : 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: W1, W3 and W4; from 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.

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