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Proceedings Paper

Chandra LETG higher-order diffraction efficiencies
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Paper Abstract

Accurate calibration of the Chandra Low Energy Transmission Grating (LETG) higher-order (|m|>1) diffraction efficiencies is vital for proper analysis of spectra obtained with the LETG's primary detector, the HRC-S, which lacks the energy resolution to distinguish different orders. Pre-flight ground calibration of the LETG was necessarily limited to sampling a relatively small subset of spectral orders and wavelengths, and virtually no higher-order data are available in the critical region between 6 and 10 Å. In this paper, we describe an analysis of diffraction efficiencies based on in-flight data obtained using the LETG's secondary detector, the ACIS-S. Using ACIS, the relative efficiency of each order can be studied out to |mλ| ~ 80 Å, which is nearly one-half of the LETG/HRC-S wavelength coverage. We find that the current models match our results well but can be improved, particularly for the even orders just longward of the Au-M edge at 6 Å.

Paper Details

Date Published: 3 February 2004
PDF: 9 pages
Proc. SPIE 5165, X-Ray and Gamma-Ray Instrumentation for Astronomy XIII, (3 February 2004); doi: 10.1117/12.509361
Show Author Affiliations
Bradford J. Wargelin, Smithsonian Astrophysical Observatory (United States)
Peter W. Ratzlaff, Smithsonian Astrophysical Observatory (United States)
Deron O. Pease, Smithsonian Astrophysical Observatory (United States)
Vinay L. Kashyap, Smithsonian Astrophysical Observatory (United States)
Jeremy J. Drake, Smithsonian Astrophysical Observatory (United States)

Published in SPIE Proceedings Vol. 5165:
X-Ray and Gamma-Ray Instrumentation for Astronomy XIII
Kathryn A. Flanagan; Oswald H. W. Siegmund, Editor(s)

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