On-orbit HRMA On-axis Effective Area

Ping Zhao

Smithsonian Astrophysical Observatory

zhao@cfa.harvard.edu, 617-496-7582

August 9, 2000

Introduction
Raytrace Simulation and Calibration Results
On-orbit HRMA On-axis Effective Area Predictions

Introduction

NASA's Chandra X-ray Observatory (CXO) was successfully launched on July 23, 1999 by the space shuttle Columbia. It has returned fruitful scientific results in the past year. CXO has unprecedented capabilities of high resolution imaging and spectroscopy over the X-ray energy band of 0.1 keV - 10 keV. The effective area of its X-ray mirror - High-Resolution Mirror Assembly (HRMA) - was measured using the X-Ray Calibration Facility (XRCF) at the Marshall Space Flight Center (MSFC) in Huntsville, AL from late 1996 to early 1997.

The on-orbit HRMA on-axis effective area predictions are generated from raytracing models and scaled by the HRMA calibration data taken at the XRCF.

SAOSAC Raytrace Simulations

The SAOSAC raytrace simulations were generated from the HRMA model which is based on measurements of HDOS metrology, Kodak assembly and the XRCF X-ray test. Its trace-shell configuration file can be found here.

The key raytrace configurations are:

Optical Constant:
- E < 0.940 keV: Gullikson '95 optical constant table.
- E > 0.940 keV: AXAF mirror witness GO flat 065 reflectivity data measured at the BNL synchrotron by Dale Graessle et al.
Reflectivity:
- Fresnel equation of multilayer reflection with Iridium (328 A), Chromium (97 A), and semi-infinite Zerodur.
- Interface reflection reduction with the Nevot-Croce factor.
Mirror Surface Roughness Scattering:
- Based on PSD produced from the HDOS metrology measurements and calculated by Leon Van Speybroeck's program "foldw1", which is based on the scattering theory by Beckmann and Spizzichino.
- Scattering table was generated on 6/23/98.
Mirror rigid body specs.
Mirror surface deformations.
Mirror cap, pre- and post-collimators, p6 ghost baffle.
Infinite source distance.

On-orbit HRMA On-axis Effective Area Predictions

The On-orbit HRMA On-axis Effective Area predictions were generated by multiplying the raytrace simulations with the XRCF calibration data scaling factors.

The XRCF calibration data scaling factors are:

E < 2 keV: the average ratio between the raytrace and FPC rerun data analyzed by Dick Edgar.
Errors include: FPC data errors; standard deviation of the FPC data; beam nonuniformity errors; aperture size errors; raytrace statistical error (this is very small).
E > 2 keV: a fourth order polynomial fit of the ratio between the raytrace and the SSD C-K continuum data analyzed by Ping Zhao. (The SSD data analysis has included pileup, pulser deadtime, relative QE and beam uniformity corrections.)
Errors include: standard deviation of SSD continuum data within each energy bin; errors from the polynomial fit; beam nonuniformity errors; aperture size errors; raytrace statistical error (this is very small).

Here are the results of on-orbit HRMA on-axis effective area predictions:

On-orbit HRMA on-axis effective area within 1 arcsec diameter: rdb table and figure.
On-orbit HRMA on-axis effective area within 10 arcsec diameter: rdb table and figure.
On-orbit HRMA on-axis effective area within 2 mm diameter aperture: rdb table and figure.
On-orbit HRMA on-axis effective area within 35 mm diameter aperture: rdb table and figure.
On-orbit HRMA on-axis effective area within 2 pi steradian: rdb table and figure.

Here is a single postscript file containing all 5 figures above.

Here are the results of on-orbit HRMA on-axis encircled energy predictions:

On-orbit HRMA on-axis encircled energy within 1 acrsec and 10 arcsec diameters: linear plot, logarithm plot and table.

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