XMM-Newton

1

M.Stuhlinger/P.Calderon, ESAC

Re-appearance of the

MOS1 CCD1 meteorite column

during revs. 1792-1801

Madrid, 23. March 2010

XMM-Newton

2

M.Stuhlinger/P.Calderon, ESAC

Review: Initiation

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

Anomaly frame [energy] Subsequent frame [energy]

XMM-Newton

3

M.Stuhlinger/P.Calderon, ESAC

Review: Impact on hardware

● CCD6 inactive.

● Damaged pixels in CCD1 causing hot column close to boresight.602

RAWY

539

11 dead pixels:RAWX 323RAWY 567-577

First diagnostic exposure taken in rev. 0961: CCD1 detail

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

XMM-Newton

4

M.Stuhlinger/P.Calderon, ESAC

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

5

M.Stuhlinger/P.Calderon, ESAC

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

6

M.Stuhlinger/P.Calderon, ESAC

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

7

M.Stuhlinger/P.Calderon, ESAC

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

8

M.Stuhlinger/P.Calderon, ESAC

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

9

M.Stuhlinger/P.Calderon, ESAC

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

10

M.Stuhlinger/P.Calderon, ESAC

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

11

M.Stuhlinger/P.Calderon, ESAC

Frequency search in FF obs.1798_0605580601

● Column modulation at long timescales or feature of harmonics?

2.6s = readout

1000 x readout

XMM-Newton

12

M.Stuhlinger/P.Calderon, ESAC

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

13

M.Stuhlinger/P.Calderon, ESAC

Future…