This version of the HRC-S MCP quantum efficiency (for LETG dispersion) reflects an improved calibration over the full range employing observations of Sirius B and PKS 2155-304.

Status:

Prior to in-flight calibration, the on-axis HRC-S QE was calibrated in the laboratory over the energy range 0.28-10.0 keV. QE calibration below 0.28 keV was incomplete, as was the HRC-S QE uniformity, required for computing the LETGS dispersed effective area which physically covers three michrochannel plates (MCPs) and spectrally covers more than two orders of magnitude. Since there is no single source available to cover this broad energy range, the calibration of the HRC-S QE and LETGS effective area has been achieved in multiple phases.

For the low energy calibration (E < 0.277 keV; wavelengths > 44 AA) we compared observations of Sirius B and HZ 43 with pure hydrogen non-LTE white dwarf emission models. For the mid-range calibration (2.0 > E > 0.277 keV; 6 < wavelengths < 44 AA) we compared observations of the active galactic nuclei PKS 2155-304 and 3C 273 with simple power-law models of their seemingly featureless continua. The residuals of the model comparisons were taken to be true residuals in the HRC-S quantum efficiency (QE) model. Additional in-flight observations of celestial sources with well-understood X-ray spectra have served to verify and fine-tune the calibration. Thus, from these studies we have derived corrections to the HRC-S QE to match the predicted and observed spectra over the full practical energy range of the LETGS.

Furthermore, from pre-flight laboratory flatfield data we have constructed an HRC-S quantum efficiency uniformity (QEU) model. Application of the QEU to our semi-empirical in-flight HRC-S QE has resulted in an improved HRC-S on-axis QE. Implementation of the HRC-S QEU with the on-axis QE now allows for the computation of effective area for any reasonable Chandra/LETGS pointing.

Data files:

• In-flight HRC-S MPC QE (version date: 11/2004)

  Positive and Negative Dispersed Quantum Efficiency;
  Based on in-flight mid-energy QE calibration with PKS 2155-304 and 3C 273,
  and low-energy QE calibration with Sirius B and HZ43;
  WITHOUT microchannel plate gaps

Previously Posted Data Files:

• In-flight HRC-S MPC QE (version date: 07/02)
  
  
• In-flight HRC-S MPC QE (version date: 12/01)
  
  
• In-flight HRC-S MPC QE (version date: 10/31/00)

  Positive and Negative Dispersed Quantum Efficiency;
  Based on in-flight mid-energy QE calibration with PKS 2155-304 and 3C 273,
  and low-energy QE calibration with Sirius B and HZ43;
  WITHOUT microchannel plate gaps

• UV/Ion Shield Transmission (updated 04/17/01)

  The updated UVIS transmission models as well as the CALDB current release version.

• In-flight HRC-S MPC QE (version date: 03/09/00)

  In-flight calibration extending the energy range below 277 eV down to 62 eV (wavelengths out to ~ 200 angstroms)

• In-flight HRC-S MPC QE (version date: 02/07/00)

• Pre-flight HRC-S MPC QE

  Pre-flight calibration covering the energy range of 277 eV to 10 keV (wavelengths of ~ 44.7 to 1.24 angstroms)

Analysis:

• HRC-S Low Energy Calibration with Sirius B and HZ 43

Last modified: 04/15/11

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