Increase of the contamination thickness of XIS0
Dec 17, 2007, the XIS team
The XIS team has found that the contamination of XIS0 is increasing
more rapidly than expected.
Figure 1 shows the history of the contamination thickness
evaluated from the regular observations of E0102-72.3, including the
latest
one on December 1st-2nd 2007. Solid curves represent the current
model for the time evolution of the contamination thickness in CALDB of
ae_xi?_contami_20070920.fits. The contamination thickness of XIS0
shows more rapid increase than that expected from the current
model. Accordingly, arfs generated with "xissimarfgen" with the
latest CALDB might underestimate the efficiency degradation by the
contamination for the XIS0 data obtained after April 2007. The amount
of the underestimation can be estimated from Figure 1.
We are planning to update the corresponding CALDB in the next
release sceduled at the end of December 2007.
Figure 1. History of the contamination thickness evaluated from the
regular
observations of E0102-72.3. Solid lines represent the current
model of contamination evolution in CALDB of
ae_xi?_contami_20070920.fits, and the dotted lines the previous model
of ae_xi?_contami_20061016.fits. Note that all the data points
in the figure are based on the analysis of ver2.x products and slightly
differ from those shown in the Technical Description.
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