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Contents:
17 Feb 2011 - ACIS peaks and sigmas
24 Mar 2011 - ACIS line fluxes
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17 Feb 2011 - Catherine's attempt to duplicate Bev's monthly XIS plots for ACIS I3 (FI) and S3 (BI). Each data point is a fit to 0.1 years worth of cold ACIS calibration source data, filtered to include only the upper corner regions like XIS and grades G02346. After some testing as to which fitting procedures were less sensitive to background variations (important for ACIS probably not as much for XIS), and robust against low signal-to-noise data, I chose to use a Gaussian plus a linear background component (mpfitfun.pro with some limits to prevent non-physical fits).
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24 Mar 2011 - CEG - The line normalizations that come out of the above fits. The first is a linear plot of the normalization versus time showing the obvious signature of radioactive decay.
(Edit added later: line normalizations is bad terminology. What I mean is the counts under the peak (Gaussian norm * Gaussian sigma * 2.51) divided by the exposure time)
Then comparing the data to the expected half-life of 2.737 years for Fe-55. There is clearly a slow reduction in quantum efficiency of 5-10% over the entire 11 years.
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