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XMM-Newton CCF Release Note
XMM-CCF-REL-239
RGS Bad Pixels
C. Gabriel
September 4, 2007
1 CCF components
Name of CCF VALDATE EVALDATE Blocks changed XSCS ag
RGS1 BADPIX 0023 2007-09-04T00:00:00 | BADPIX NO
2 Changes
This release adresses an issue concerning bad segments, which has already been discussed in a former
CCF release note (XMM-CCF-REL-226). Flagging of two areas with increased osets ("hot spots"),
on both upper part sides of CCD 1 in RGS1, so each one corresponding to a readout node became
necessary. This was done so far through a number of advisory hot segments masking the area of
the spots, as long as they were not uploaded to the instrument. From revolution 1416 these hot
segments are uploaded to the instrument, to avoid increased telemetry.
3 Analysis
As part of the continous monitoring of the RGS instruments, oset maps are produced, as the
averages of the diagnostic images over three consecutive revolutions. They are then taken into the
ODF data for the oset subtraction. The two hot spots are clearly seen in Figure 1a, showing
the oset map corresponding to revolution 1323. The hot spots are attributed to stress produced
in CCD1 at the bond places. The temporal evolution of the \spot" central pixel signal (Fig. 1b)
shows that the signal is still increasing, although attening, and has surpassed the threshold level.
This means that a denitive signal is contributing more and more to increased telemetry (although
part of the spots are ltered on board). Since further expansion of the spot could be compromising
telemetry rates, provision has been taken to upload bad column segments, masking fully o the spot
areas.
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Figure 1: Left: RGS1 - CCD1 oset map showing the two "hot spots". Right: time evolution of
signal from one spot central pixel.
4 Scientic Impact of this Update
The start date of validity is set to 4 September 2007 when the new bad pixel tables including masking
of the hot spots started to be uploaded to the instrument. SAS will notice through this CCF that
the masked regions are not telemetered.
5 Estimated Scientic Quality
The inclusion of the new hot segments in this CCF will insure a proper calculation of eective areas.
6 Expected Updates
Further analysis of bad pixels with diagnostic and science data should lead to updates, although
this is expected to happen very infrequently.
7 Test procedures
General checks:
 use fv (or another ts viewer) for le inspection. It should contain 2 binary extensions (BAD-
PIX and BADPIX1)
 use the SAS task CALVIEW to see if the CAL digests and uses the new les.
 check that the dierences between RGS1 BADPIX 0020 and 0023 are exclusively the change
from advisory ("H") to uploaded ("h") of the segments corresponding to the hot spots.

XMM-Newton CCF Release XMM-CCF-REL-239 Page: 3
8 Summary of the test results
The ts viewer fv was used to inspect both CCF les, wrt their structure, validity dates and contents
of the rst extension (BADPIX). Everything OK.
The SAS task cifbuild was run several times using data corresponding to periods covered and
not covered by this CCF in order to check the correct selections. Selections were correctly done.
The SAS task calview was used to prove that these calibration les are ingested correctly by the
CAL, by pointing to the dierent Calibration Index Files and producing bad pixel plots.
Finally, fdi (FTOOLS) has been used to check that the only dierences to the former valid
bad pixel CCF le (RGS1 BADPIX 0020) are that all segments corresponding to the hot spots are
marked with "h" for uploaded instead of "H" for advisory.