WFCAM update from CASU
======================

The final stages of the tuning and implementation of the summit processing 
and standard processing pipelines for WFCAM have been completed using 05A 
science observations.  Apart from minor enhancements and bug fixes this
phase of development is now complete.

The first reduction of all 05A data (Version 1) was finished by the end 
of July and made available for transfer to WFAU in Edinburgh.  The SV1 subset 
of this data, ie. UKIDSS SV data from to April 8th-19th, was released to the 
UKIDSS SV testing community via the WFAU science archive on July 22nd and
assorted feedback on the properties of this release was obtained at the
two SV meetings held in Edinburgh on August 18th and Cambridge on September
21st.

Reprocessing of 05A for Version 2 began mid-August to take into account three 
main issues: a bug in the pipeline version of the stacking algorithm which 
was effectively clipping bright pixels leading to a significant non-linearity 
problem for the brightest sources and concommittant knock-on effect for the 
derived magnitudes of faint sources; an updated and improved set of colour 
equations were used to revisit the photometric calibration based on 2MASS 
which solved the anomalies noticed in comparisons with the UKIRT FS sequences;
the remaining missing standard catalogue parameters, mainly error estimates 
and Petrosian-like flux measures, were incorporated.  Version 2. of the 
pipeline processed data for 05A was completed early-October and an SV1 subset
by the end of August.

Cross-talk correction has now been included in the Cambridge pipeline and
is being routinely used (and science tested) in processing 05B data.  The 
practicalities of persistence correction are still being addressed and this
has not yet been implemented.  Debugging and testing the cross-talk correction
lead to slight delays in beginning the processing of 05B data.

We anticipate producing a Version 3 of pipeline processed data for 05A when
more detailed comments on the earlier versions are fedback from the SV 
community and when we are satisfied with the performance of the cross-talk
and persistence removal algorithms.  Related to this, the development of PSF 
estimation and fitting (phases 1,2) is completed and will be added to the 05A 
catalogues by the end of 2005.  If this proves satisfactory after community 
feedback the 05B data will be next in line.


The raw data, which arrives on tape roughly 2 weeks after the data is taken,
is verified and ingested into the raw WFCAM data archive within a few days
of arrival (see http://archive.ast.cam.ac.uk/wfcam/). Transfers of raw WFCAM 
UKIDSS and calibration data to the ESO archive are handled by an ESO-supplied
script and are complete to the end of semester 05A.

The status of the pipeline processing is automatically monitored and made 
available on the web pages at http://apm15.ast.cam.ac.uk/wfcam/ together with 
other more general WFCAM information.  

After processing, the derived quality control (QC) and other useful header 
information are now being ingested into a prototype WFCAM DQC database which 
is being used, among other things, to test automatic generation of UKIDSS 
survey progress web pages (see http://apm15.ast.cam.ac.uk/docs/wfcam/
science-verification/topic for a trial example).

Many improvements to the summit pipeline have been made, particularly 
related to speed issues.  The summit pipeline has been updated with the 
latest calibration frames produced in Cambridge (master flats and confidence 
maps) and new tools for automatically generating master calibration
frames at the summit have been written.

There was a WFCAM photometric calibration meeting in Cambridge on September 
20th (attended by Simon Hodgkin, Paul Hewett, Steve Warren & Nick Cross). 
With the improved 2MASS -> WFCAM colour equations and a correction for the 
H-band offset of 2MASS from the Vega system, good agreement is now obtained 
between the UKIRT FS system and the 2MASS-calibrated WFCAM system.  An 
investigation into residual spatial systematics has demonstrated that these 
are at a level less than +/-1% over the entire array.  A draft version of 
this report is available at http://www.ast.cam.ac.uk/vdfs/docs/reports/
wfcam_photcal_report.pdf

Further reports including the CASU analysis of SV data is discussed in the 
web documents available at http://www.ast.cam.ac.uk/vdfs/docs/reports/sv/ 
and our internal assessment of the SV science products is available
http://apm15.ast.cam.ac.uk/docs/wfcam/science-verification.


Summary of Cambridge processing
===============================

Version  Semester    Images        Catalogues     Calibration     Timeline

  #1       05A     stacking bug    no errors      2MASS old ce    Jul 2005
                                   or Petrosian
                                   fluxes

  #2       05A     fixed stacks    full standard  2MASS new ce    Sep 2005
                   better skies    parameter set

           05A     (as above)    + PSF parameters  (as above)     Dec 2005
                  
  #3       05A   + cross-talk    + Sersic          (as above)     Mar 2006     
                 + persistence?
                   removed

--------------------------------------------------------------------------

  #1       05B   + cross-talk      full standard  2MASS new ce    Oct 2005  
                   removed         parameter set                      --->

  #2       05B   + persistence?  + PSF parameters  (as above)     Apr 2006
                   removed         Sersic