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 ( mkBADPIX.pl ) which takes the raw data and outputs the tarred, gzipped badpixel files to go on the web.
Creation -- What mkBADPIX.pl 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 BADPIX5x.pl 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!