Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://xmm.vilspa.esa.es/docs/documents/CAL-SRN-0004-1-0.ps.gz Äàòà èçìåíåíèÿ: Wed Jan 3 15:10:22 2001 Äàòà èíäåêñèðîâàíèÿ: Mon Oct 1 21:29:29 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: http astrokuban.info astrokuban

XMM­Newton CCF Release Note
XMM­CCF­REL­4
EPIC Bad Pixels
D Lumb
October 3, 2000
1 CCF components
Name of CCF VALDATE List of Blocks
changed
CAL VERSION XSCS flag
EMOS1 BADPIX 0006 2000­01­01T00:00:00 BADPIX YES
EMOS2 BADPIX 0006 2000­01­01T00:00:00 BADPIX YES
EPN BADPIX 0008 2000­01­01T00:00:00 BADPIX
ADUOFFSET
YES
2 Changes
There is a range of phenomena that can be classed as bad pixels. The most obvious manifestation
is of individual pixels which exhibit a small above­threshold signal in most readout frames. These
are generally blanked out of the telemetry by the on­board electronics. Occasionally a new bad
pixel can occur, and the cycle of database updates can take some weeks to implement its rejection
and implementation in the calibration files. The user might recognise these as a bright pixel in an
image, and a spurious low energy emission line feature. Some bad pixels occur at such a low duty
cycle that they are not implemented on­board, and indeed may be transient features. Such ``warm''
pixels and the temporarily un­flagged hot pixels can be detected and flagged by running the SAS
task badpixfind, and applying the spatial mask filter which results.
The OFFSET extension of the PN files includes a value for the ADU offsets applied to individual
whole columns, in order to reduce telemetered rates of low level pixels. This offset value must then
be subtracted out on­ground to obtain the correct energy value.
1

XMM­Newton CCF Release XMM­CCF­REL­4 Page: 2
3 Scientific Impact of this Update
First Release
4 Estimated Scientific Quality
The response generation tasks make a rudimentary correction for the consequent area losses, but
secondary effects of changing pattern types can occur (for example bi­pixel events become single
pixel events). As long as a bad pixel does not occur at the peak of the PSF or extraction region,
the errors in correction will not be significant.
Currently the CAL does not handle the PN offset columns, so a small number of columns have
the incorrect energy values removed via hard­coded numbers.
5 Expected Updates
Whenever there is a new release of badpixels for on­board the CCF file will be updated. Not­
uplinked bad pixels which are found to be stable and should be placed in the file will be added as
necessary