The ASCII files badpix_[ABCD]_DDMMYY (where ABCD is the applicability
period, see README in this dir. and DDMMYY is the creation date of the
table) list bad pixels and columns in the following format:

ccdid	chipx0	chipx1	chipy0	chipy1

The latter 4 values give a rectangle to exclude, either a single pixel or a
column (sometimes several adjacent ones), whole or partial. The hot pixels
are found by visual inspection of chip images. I tried to be more
conservative (i.e. list more bad pixels) than the standard CALDB bad pixel
table.  All pre-flight bad columns (excluded onboard) are included here,
plus adjacent columns on each side (since they produce incorrect
grades). Node boundaries are also excluded since they produce incorrect
grades. However, unlike the standard tables, I did not exclude good pixels
and columns adjacent to each true bad pix/col.

There are also the same tables in FITS format. They are made by a wrapper
tool (by Leon VanSpeybroek) using the CALDB files as templates. I didn't
care to update the header keywords so many are wrong (e.g.  FP_TEMP) but it
shouldn't be important. I hope they work.

These tables are used by the tool badpixfilter (see the file COOKBOOK
somewhere in these directories) and also for the creation of the exposure
maps.

The default tables include (that is, result in filtering out of) the chip
edges (chipy=1-9) which are affected by the framestore shadow. The *noedge
versions of the badpix files do not include (i.e., result in leaving in)
these edges. It is recommended that the edges are filtered out in both
science and bg files, and a corresponding badpix table is used for the
exposure map creation. Note that for consistency with CALDB, most bg files
in this dir. are created using the *noedge version, so they require this
additional filtering step.

---
versions 280605 are same as 041104, but all bad columns 10-1023 instead of
2-1023, to avoid overlap with the excluded edge (a problem for Vikhlinin's
exposure maps)
