LETGS Effective Area and HRC-S QEU
Chandra LETGS Calibration Review 31/10/01:
Effective Area and HRC-S Quantum Efficiency Uniformity
November 6, 2001
The relative quantum efficiency of the HRC-S central plate obtained by
the HRC laboratory at C Kalpha (0.277 keV; 44.76 AA). The data are
averaged over 3 half-taps in the cross-dispersion direction,
corresponding to the observatory z location of the current LETG+HRC-S
aim point, are normalised to 1 at the observatory y location of the
aim point, and are plotted here as a function of arbitrary observatory
y coordinate. The solid curve represents a polynomial fit to these
data; deviations are consistent with Poisson noise.
A surface plot of the QE uniformity for the central HRC-S plate,
illustrated as a function of energy and first order dispersion
coordinate. Surfaces for each plate were derived from polynomial fits
to QEU data such as that illustrated in the previous figure, and were
used to derive the QEU map for the detector as a function of position
and energy.
The standard CIAO LETG+HRC-S extraction efficiency determined from
MARX ray trace simulations.
The MARX extraction efficiency derived from parameters supplied by Jelle
Kaastra for the standard SRON extraction region, determined from
MARX ray trace simulations.
Insert Deron figs and captions in here:
Low E correction curve; fit to Sirius in one order
higher E correction curve; fit to PKS
Comparisons of CXC and SRON effective area curves, supplied by
J.Kaastra. Note that the SRON effective area analysis adopted
slightly different parameters for PKS2155-304, including a different
ISM column density. Nearly all the differences in area between CXC and
SRON can be attributed to these different parameters, the slightly
different spectral extraction regions and modifications to the UVIS
optical depth effected by the latter group.
Comments and questions to: Jeremy Drake
Last modified:
06/14/02
