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MOS1 Timing Mode noise echo of the meteorite column Madrid, 23. March 2009. Discovery history:. During analyses of MOS1 timing mode exposures. My MOS1 timing mode spectrum of highly absorbed source 1E1740.7-2942 looks very different to MOS2/pn at low energies.
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MOS1 Timing Mode noise echo of the meteorite column Madrid, 23. March 2009 M.Stuhlinger, ESAC
Discovery history: • During analyses of MOS1 timing mode exposures. • My MOS1 timing mode spectrum of highly absorbed source 1E1740.7-2942 looks very different to MOS2/pn at low energies. • Same spectrum extracted by Carlos Gabriel agrees with MOS2 and does not show low energy features. M.Stuhlinger, ESAC
Different spectra extractions cause different appearance M.Stuhlinger, ESAC
Discovery history: • During analyses of MOS1 timing mode exposures. • My MOS1 timing mode spectrum of highly absorbed source 1E1740.7-2942 looks very different to MOS2/pn at low energies. • Same spectrum extracted by Carlos Gabriel agrees with MOS2 and does not show low energy features. • Where do “my” low energy counts come from? Columns 320-327 show noise component shifted to lower energies with increasing RAWX. M.Stuhlinger, ESAC
1E1740.7-2942 M.Stuhlinger, ESAC
1E1740.7-2942 RAWX325 RAWX324 RAWX323 RAWX322 RAWX321 RAWX320 M.Stuhlinger, ESAC
Discovery: • During analyses of MOS1 timing mode exposures. • My MOS1 timing mode spectrum of highly absorbed source 1E1740.7-2942 looks very different to MOS2/pn at low energies. • Same spectrum extracted by Carlos Gabriel agrees with MOS2 and does not show low energy features. • Where do “my” low energy the counts come from? Columns 322-325 show noise component shifted to lower energies with increasing RAWX. • Why the difference? We both exclude the hot column RAWX=319. Carlos used RAWX [300:316] (left PSF wing only), I used RAWX [300:317] or [321:330] (both PSF wings with gap). M.Stuhlinger, ESAC
6 pixels to be ignored 1E1740.7-2942 M.Stuhlinger, ESAC
RAWX 320 RAWX 319 RAWX 321 RAWX 322 RAWX 323 PI RAWX 324 RAWX 325 RAWX MOS1 1E1740.7-2942 (rev.1065): PI versus RAWX M.Stuhlinger, ESAC
PI RAWX MOS1 Swift J1753.5-0127 (rev.1152): PI versus RAWX RAWX 320 RAWX 321 RAWX 319 RAWX 322 RAWX 323 RAWX 324 RAWX 325 M.Stuhlinger, ESAC
PI RAWX MOS1 4U0142+61 (rev.1300): PI versus RAWX RAWX 320 RAWX 321 RAWX 319 RAWX 322 RAWX 323 RAWX 324 RAWX 325 M.Stuhlinger, ESAC
Conclusions: • Noise echo of meteorite column in RAWX [320:325] is common feature in MOS1 timing modes. • Most probable noise echo is created within serial readout process. • For extraction of MOS1 timing mode spectra (Rev.>961): Better ignore RAWX [318:325] • Large fraction of the right (higher RAWX values) PSF wing is lost! • Already recommended: Avoid MOS1 observations in timing mode. M.Stuhlinger, ESAC