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The ASTRO-H SXT Performance to the Large Off-Set AnglesThe X-ray astronomy satellite ASTRO-H, which is the 6th Japanese X-ray astronomy satellite and is renamed Hitomi after launch, is designed to observe celestial X-ray objects in a wide energy band from a few hundred eV to 600 keV. The Soft X-ray Telescopes (SXTs) onboard ASTRO-H play a role of collecting and imaging X-rays up to approximately 12 keV. Although the field of view of the SXT is approximately 15' (FWHM), due to the thin-foil-nested Wolter-I type optics adopted in the SXTs, X-rays out of the field of view can reach the focal plane without experiencing a normal double reflection. This component is referred to as 'stray light'. Owing to investigation of the stray light so far, 'secondary reflection' is now identified as the main component of the stray light, which is composed of X-rays reflected only by secondary reflectors. In order to cut the secondary reflections, a 'pre-collimator' is equipped on top of the SXTs. However, we cannot cut all the stray lights with the pre-collimator in some off-axis angle domain. In this study, we measure the brightness of the stray light of the SXTs at some representative off-axis angles by using the ISAS X-ray beam line. ASTRO-H is equipped with two modules of the SXT; one is for the Soft X-ray Spectrometer (SXS), an X-ray calorimeter, and the other is for the Soft X-ray Imager (SXI), an X-ray CCD camera. These SXT modules are called SXT-S and SXT-I, respectively. Of the two detector systems, the SXI has a large field of view, a square with 38' on a side. To cope with this, we have made a mosaic mapping of the stray light at a representative off-axis angle of 30' in the X-ray beam line at the Institute of Space and Astronautical Science. The effective area of the brightest secondary reflection is found of order approximately 0.1% of the on-axis effective area at the energy of 1.49 keV. The other components are not so bright (less than 5 x 10(exp -4) times smaller than the on-axis effective area). On the other hand, we have found that the effective area of the stray light in the SXS field of view (approximately 3' x 3') at large off-axis angles (greater than 15') are approximately 1(exp -4) times smaller than the on-axis effective area (approximately 590 sq cm at 1.49 keV).
Document ID
20170006119
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
External Source(s)
Authors
Sato, Toshiki
(Tokyo Metropolitan Univ. Tokyo, Japan)
Iizuka, Ryo
(Japan Aerospace Exploration Agency Sagamihara, Japan)
Mori, Hideyuki
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Hayashi, Takayuki
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Maeda, Yoshitomo
(Japan Aerospace Exploration Agency Sagamihara, Japan)
Ishida, Manabu
(Japan Aerospace Exploration Agency Sagamihara, Japan)
Kikuchi, Naomichi
(Tokyo Metropolitan Univ. Tokyo, Japan)
Kurashima, Sho
(Tokyo Metropolitan Univ. Tokyo, Japan)
Nakaniwa, Nozomi
(Tokyo Metropolitan Univ. Tokyo, Japan)
Okajima, Takashi
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Soong, Yang
(Maryland Univ. College Park, MD, United States)
Serlemitsos, Peter J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
July 6, 2017
Publication Date
July 18, 2016
Publication Information
Publication: SPIE Proceedings
Publisher: SPIE
Volume: 9905
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN43825
Meeting Information
Meeting: Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray
Location: Edinburgh
Country: United Kingdom
Start Date: June 26, 2016
End Date: July 1, 2016
Sponsors: International Society for Optical Engineering
Funding Number(s)
CONTRACT_GRANT: NNG17PT01A
Distribution Limits
Public
Copyright
Other
Keywords
X-rays
Soft X-ray Telescopes (SXTs)
stray lights
ASTRO-H/Hitomi
Wolter Type-I optics

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