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### Journal of Astronomical Telescopes, Instruments, and Systems • Open Access

Observational artifacts of Nuclear Spectroscopic Telescope Array: ghost rays and stray light
Author(s): Kristin K. Madsen; Finn E. Christensen; William W. Craig; Karl W. Forster; Brian W. Grefenstette; Fiona A. Harrison; Hiromasa Miyasaka; Vikram Rana

Paper Abstract

The Nuclear Spectroscopic Telescope Array (NuSTAR) launched in June 2012, flies two conical approximation Wolter-I mirrors at the end of a 10.15-m mast. The optics are coated with multilayers of Pt/C and W/Si that operate from 3 to 80 keV. Since the optical path is not shrouded, aperture stops are used to limit the field of view (FoV) from background and sources outside the FoV. However, there is still a sliver of sky ( $∼ 1.0 deg$ to 4.0 deg) where photons may bypass the optics altogether and fall directly on the detector array. We term these photons stray light. Additionally, there are also photons that do not undergo the focused double reflections in the optics, and we term these ghost rays. We present detailed analysis and characterization of these two components and discuss how they impact observations. Finally, we discuss how they could have been prevented and should be in future observatories.

Paper Details

Date Published: 27 October 2017
PDF: 13 pages
J. Astron. Telesc. Instrum. Syst. 3(4) 044003 doi: 10.1117/1.JATIS.3.4.044003
Published in: Journal of Astronomical Telescopes, Instruments, and Systems Volume 3, Issue 4
Show Author Affiliations
Kristin K. Madsen, California Institute of Technology (United States)
Finn E. Christensen, DTU Space (Denmark)
William W. Craig, Univ. of California, Berkeley (United States)
Karl W. Forster, California Institute of Technology (United States)
Brian W. Grefenstette, California Institute of Technology (United States)
Fiona A. Harrison, California Institute of Technology (United States)
Hiromasa Miyasaka, California Institute of Technology (United States)
Vikram Rana, California Institute of Technology (United States)

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