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Last modified: 26 October 2016

URL: http://cxc.harvard.edu/ciao/why/hrc_qe.html

HRC-S QE/QEU


HRC-S QE vN0011

A new mean quantum efficiency (QE) file was released for HRC-S in CALDB 4.4.7 (15 December 2011).

Following in-flight calibration of the low energy QE, models of flux vs energy and parameter estimates for the two main calibration standards (HZ43 and Sirius B) underwent significant revisions. The latest non-LTE pure hydrogen model atmospheres computed by the Tubingen group have been used to devise a new low energy calibration.

These figures show the residuals between LETG+HRC-S observations and the fiducial model before and after modifications to the HRC-S quantum efficiency.

The new file will be used by default when creating exposure maps or grating ARFs in CIAO.

HRC-S QEU vN0006

The HRC-S QEU file was upgraded to version N0006 in CALDB 4.4.5 (30 June 2011). Version N0006 of the HRC-S QEU takes into account the very slow QE degradation with time.

This QEU fixes the time-dependence in the HRC-S for all observational periods from 1999 through the present. Since the changes are normalized to be zero at 2008, the gARFs and exposure maps will not change for observations with DATE-OBS between 2008-01-01T00:00:00 and 2009-01-01T00:00:00. All other response will be slightly modified, by about half a percent per year difference from mid-year 2008.

The most recent QE and QEU calibration will automatically be chosen from the CALDB when creating exposure maps, imaging ARFs, or grating ARFs for HRC-S data.


Last modified: 26 October 2016
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