status T0004

From: Yannick Mellier <mellier_at_iap.fr>
Date: Fri, 04 May 2007 08:49:07 +0200

    Dear All

   Just a summary of T0004:

- STEP1: QFITS-in , grading, weight maps: all done , beeing transferred
to CADC (hopefully). 15850 Megacam images processed, with 2914 new for
2006.

- STEP2: W1 , W2 and W4 are done (stacks, catalogues, chi2 images,
QFITS-outs, ugriz color-color plots).

We are still checking the data quality:
- W2 is not checked yet.
- W1 is ok in all bands, W4 is ok in g, r and i, but we have a serious
photometric calibration problem in W4-u: 0.20 mag off with respect to
SDSS. We also see a 0.05 mag in z. We have released three times W4
since April 15, in order to check the Terapix processes, and ask
Jean-Charles confirmation of ZPs. For the moment we do not have
explanation of this. The 0.2 mag. offset is also visible on the
stellar-color color plots, so this is not a SDSS calibration problem.
Note that there is one W1 field for which we do have SDSS data and the u
is perfect and the z as well. We therefore believe there is no problem
at the Terapix processing level (but we only have one common field W1
CFHTLS-SDSS).

- W3 will start between today and May 10.

Deep 25% and 85%: Deep-25% u and g done. r, i z in the queue. The
stacks are demanding in terms of disk space, but we can do them in two
days per filter. Since T0001/T0002/T0003 were ok, and because we can
produce all Deep in one week or so, we do not envision any issues
regarding astrometry, photometry, etc...

- In view of this, we think T0004 will be 100% ready by May 20.

    Cheers


    Fred, Yannick and Terapix
Received on Thu May 03 2007 - 20:49:14 HST