This page contains BADPIX masks for the WFI.
These BADPIX mask files contain 8 individual BADPIX files - one for each of the WFI chips.

NOTE: A detailed report on the creation of the BADPIX masks can be found here.
The following is a summary of the processes and the resulting BADPIX masks for WFI.



I have written a PERL script ( ) which takes the raw data and outputs the tarred, gzipped badpixel files to go on the web.

Creation -- What does

They are created in the following way:

  • Take: 5 Bias images, 5 Domeflats with low counts (~5000 counts), 5 Domeflats with high counts (~20,000 counts)
  • Overscan and trim all images
  • Zerocombine the Bias images
  • Bias subtract the Domeflat images
  • Flatcombine the domeflats with high counts - FLATHIGH
  • Flatcombine the domeflats with low counts - FLATLOW
  • mscarith FLATLOW.fits / FLATHIGH.fits FLATLHRATIO.fits
  • mscsplit FLATLHRATIO.fits
  • ccdmask FLATLHRATIOx.fits with the following parameters set:

                    Image Reduction and Analysis Facility
PACKAGE = ccdred
   TASK = ccdmask

image   =                       Input image
mask    =                       Output pixel mask
(ncmed  =                    7) Column box size for median level calculation
(nlmed  =                    7) Line box size for median level calculation
(ncsig  =                   15) Column box size for sigma calculation
(nlsig  =                   15) Line box size for sigma calculation
(lsigma =                  20.) Low clipping sigma
(hsigma =                  20.) High clipping sigma
(ngood  =                    5) Minimum column length of good pixel seqments
(linterp=                    2) Mask value for line interpolation 
(cinterp=                    3) Mask value for column interpolation 
(eqinter=                    2) Mask value for equal interpolation
(mode   =                   ql)

NEW BADPIX masks (sigma=20)

OLD BADPIX masks (made with a much lower sigma=5)

See here for the way the masks used to be created.

How to use the BADPIX masks

The file you download has 8 badpix masks, one for each chip. They are labelled BADPIX5?.pl representing the official names of the 8 chips. These are NOT perl scripts (though the labelling is misleading). These are the files that you indicate in the FIXFILE keyword of CCDPROC . Simply enter the names of the badpix files there and run CCDPROC . That's all there is to it!