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Re-appearance of the MOS1 CCD1 meteorite column during revs. 1792-1801 Madrid, 23. March 2010

Re-appearance of the MOS1 CCD1 meteorite column during revs. 1792-1801 Madrid, 23. March 2010. Review: Initiation. Presumably micro-meteorite impact into MOS1 in rev. 0961. Anomaly frame [energy] Subsequent frame [energy]. Review: Impact on hardware. CCD6 inactive.

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Re-appearance of the MOS1 CCD1 meteorite column during revs. 1792-1801 Madrid, 23. March 2010

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  1. Re-appearance of the MOS1 CCD1 meteorite column during revs. 1792-1801 Madrid, 23. March 2010 M.Stuhlinger/P.Calderon, ESAC

  2. Review: Initiation • Presumably micro-meteorite impact into MOS1 in rev. 0961. Anomaly frame [energy] Subsequent frame [energy] M.Stuhlinger/P.Calderon, ESAC

  3. Review: Impact on hardware • CCD6 inactive. • Damaged pixels in CCD1 causing hot column close to boresight. 602 RAWY 539 First diagnostic exposure taken in rev. 0961: CCD1 detail 11 dead pixels: RAWX 323 RAWY 567-577 New hot column RAWX 323: 3 (9) pixels next to pn (RGS) prime boresight position M.Stuhlinger/P.Calderon, ESAC

  4. 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. M.Stuhlinger/P.Calderon, ESAC

  5. 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 M.Stuhlinger/P.Calderon, ESAC

  6. 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. M.Stuhlinger/P.Calderon, ESAC

  7. 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 M.Stuhlinger/P.Calderon, ESAC

  8. 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). M.Stuhlinger/P.Calderon, ESAC

  9. 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. M.Stuhlinger/P.Calderon, ESAC

  10. 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 M.Stuhlinger/P.Calderon, ESAC

  11. Frequency search in FF obs.1798_0605580601 • Column modulation at long timescales or feature of harmonics? 2.6s = readout 1000 x readout M.Stuhlinger/P.Calderon, ESAC

  12. 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? M.Stuhlinger/P.Calderon, ESAC

  13. Future… M.Stuhlinger/P.Calderon, ESAC

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