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					   Re-appearance of the

MOS1 CCD1 meteorite column

   during revs. 1792-1801




                               Madrid, 23. March 2010



                             XMM-Newton
                            M.Stuhlinger/P.Calderon, ESAC

                                                     1
                        Review: Initiation

● Presumably micro-meteorite impact into MOS1 in rev. 0961.

  Anomaly frame [energy]              Subsequent frame [energy]




                                                   XMM-Newton
                                                  M.Stuhlinger/P.Calderon, ESAC

                                                                           2
                   Review: Impact on hardware

● CCD6 inactive.

● Damaged pixels in CCD1 causing hot column close to boresight.
                                                                      602
                                 First diagnostic exposure taken
                                 in rev. 0961: CCD1 detail



               11 dead pixels:
               RAWX 323                                               RAWY
               RAWY 567-577



                                 New hot column RAWX 323:
                                 3 (9) pixels next to pn (RGS)
                                 prime boresight position
                                                                      539

                                                           XMM-Newton
                                                          M.Stuhlinger/P.Calderon, ESAC

                                                                                   3
                     Review: Corrective actions

● Investigated meteorite column offset in FF, LW and SW mode
  diagnostics:
   • Same increased column offset (by ~19 ADU) measured for all
     imaging modes.

● Investigated impact of meteorite column offset for science
  observations:
   • Calibration line energies in calclosed observations were shifted
     by ~20 ADU.
   • Similar offset as in diagnostic exposures.
   • Thus just an additive offset.

● Correction can be done by changing of onboard-offset table to make
  the meteorite column available for science again.


                                                      XMM-Newton
                                                     M.Stuhlinger/P.Calderon, ESAC

                                                                              4
               Review: Monitoring of column offset

● Regular FF, LW and SW diagnostic exposures in routine calibration.
   • Column offset showed exponential long term decay.

● On-board offset table value decreased by 10 ADU (123 =>113 ADU)
  after ~600 revolutions (active since rev. 1690).




                                                              Topic of this talk




                                                    XMM-Newton
                                                   M.Stuhlinger/P.Calderon, ESAC

                                                                            5
         Re-appearances since on-board offset table change

● Detections usually by Blanca Juárez (last remaining InsCon).

● During first eclipse phase after correction in single observations.
  (revs.1122-1130).

● Few single observations, e.g. slew 9152300002.

● Short phase in revs. 1537+1538.
Offset in on-board table decreased (~rev.1690).

● After change, column was mostly hot in revs. 1698-1701.

● Longer phase in revs. 1792-1801.


                                                        XMM-Newton
                                                       M.Stuhlinger/P.Calderon, ESAC

                                                                                6
          Trend during re-appearance in revs. 1792-1802

● Diagnostic exposures to measure the column offset during a “hot
  phase” are only available for latest occurrence due to coincidence
  with routine calibration observation in rev. 1796 (Capella).
                                                        500 sec bins




                                                      XMM-Newton
                                                     M.Stuhlinger/P.Calderon, ESAC

                                                                              7
              First diagnostics during re-appearance

● Diagnostics in routine cal. observation 1796-0510780401 (Capella):
     column offset about 7 ADU higher (119 ADU) than expected by
     the decay model (112 ADU).




                                                     XMM-Newton
                                                    M.Stuhlinger/P.Calderon, ESAC

                                                                             8
                Detection due to telemetry anomaly

● Independent notification of hot meteorite column by Pedro Calderon
  via strange behaviour of MOS1 telemetry, e.g. in rev.1800.

● MOS1 telemetry
  showed flares
  whereas MOS2
  telemetry was
  constant.



● Meteorite column is
  cause of telemetry
  anomaly.


                                                     XMM-Newton
                                                    M.Stuhlinger/P.Calderon, ESAC

                                                                             9
                Frequency search in SW obs.1800_0412600801

● Except readout time and its harmonics, no significant frequency was
  found inside the data.
     0.3 s = readout




                       Harmonics of readout frequency




                                                         XMM-Newton
                                                        M.Stuhlinger/P.Calderon, ESAC

                                                                                10
          Frequency search in FF obs.1798_0605580601

● Column modulation at long timescales or feature of harmonics?




                                     2.6s = readout




                                                       XMM-Newton        1000 x
                                                      M.Stuhlinger/P.Calderon, readout
                                                                                ESAC

                                                                                11
                                  Summary

● If the meteorite column appears hot, it is due to increase of the column
  offset.

● No time correlation was found for frequencies higher f>0.01 Hz.

● Possible correlations at very low frequencies, might be just features in
  harmonics of light curve binning/readout frequency harmonics(?).



Still open questions:

● Why does the meteorite column occasionally re-appears hot for some
  observations / time periods?

● What causes the (short term) variation of the column offset?


                                                             XMM-Newton
                                                            M.Stuhlinger/P.Calderon, ESAC

                                                                                    12
Future…




           XMM-Newton
          M.Stuhlinger/P.Calderon, ESAC

                                  13