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Journal of Astronomical Telescopes, Instruments, and Systems

Examining the angular resolution of the ASTRO-H’s soft x-ray telescopes
Author(s): Toshiki Sato; Ryo Iizuka; Manabu Ishida; Naomichi Kikuchi; Yoshitomo Maeda; Sho Kurashima; Nozomi Nakaniwa; Kazuki Tomikawa; Takayuki Hayashi; Hideyuki Mori; Takashi Okajima; Peter J. Serlemitsos; Yang Soong; Takanori Izumiya; Sari Minami
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Paper Abstract

The international x-ray observatory ASTRO-H was renamed “Hitomi” after launch. It covers a wide energy range from a few hundred eV to 600 keV. It is equipped with two soft x-ray telescopes (SXTs: SXT-I and SXT-S) for imaging the soft x-ray sky up to ∼12  keV, which focus an image onto the respective focal-plane detectors: CCD camera (SXI) and a calorimeter (SXS). The SXTs are fabricated in a quadrant unit. The angular resolution in half-power diameter (HPD) of each quadrant of the SXTs ranges between 1.1 and 1.4 arc min at 4.51 keV. It was also found that one quadrant has an energy dependence on the HPD. We examine the angular resolution with “spot scan” measurements. In order to understand the cause of imaging capability deterioration and to reflect it to the future telescope development, we carried out spot scan measurements, in which we illuminate all over the aperture of each quadrant with a square beam 8 mm on a side. Based on the scan results, we made “maps” of image blurring and a focus position. The former and the latter reflect figure error and positioning error, respectively, of the foils that are within the incident 8  mm×8  mm beam. As a result, we estimated those errors in a quadrant to be ∼0.9 to 1.0 and ∼0.6 to 0.9 arc min, respectively. We found that the larger the positioning error in a quadrant is, the larger its HPD is. The HPD map, which manifests the local image blurring, is very similar from quadrant to quadrant, but the map of the focus position is different from location to location in each telescope. It is also found that the difference in local performance causes energy dependence of the HPD.

Paper Details

Date Published: 7 October 2016
PDF: 11 pages
J. Astron. Telesc. Instrum. Syst. 2(4) 044001 doi: 10.1117/1.JATIS.2.4.044001
Published in: Journal of Astronomical Telescopes, Instruments, and Systems Volume 2, Issue 4
Show Author Affiliations
Toshiki Sato, Tokyo Metropolitan Univ. (Japan)
Institute of Space and Astronautical Science (Japan)
Ryo Iizuka, Institute of Space and Astronautical Science (Japan)
Manabu Ishida, Institute of Space and Astronautical Science (Japan)
Graduate Univ. for Advanced Studies (Japan)
Naomichi Kikuchi, Tokyo Metropolitan Univ. (Japan)
Institute of Space and Astronautical Science (Japan)
Yoshitomo Maeda, Institute of Space and Astronautical Science (Japan)
Graduate Univ. for Advanced Studies (Japan)
Sho Kurashima, Tokyo Metropolitan Univ. (Japan)
Institute of Space and Astronautical Science (Japan)
Nozomi Nakaniwa, Tokyo Metropolitan Univ. (Japan)
Institute of Space and Astronautical Science (Japan)
Kazuki Tomikawa, Tokyo Metropolitan Univ. (Japan)
Institute of Space and Astronautical Science (Japan)
Takayuki Hayashi, NASA Goddard Space Flight Ctr. (United States)
Nagoya Univ. (Japan)
Institute of Space and Astronautical Science (Japan)
Hideyuki Mori, NASA Goddard Space Flight Ctr. (United States)
Nagoya Univ. (Japan)
Takashi Okajima, NASA Goddard Space Flight Ctr. (United States)
Peter J. Serlemitsos, NASA Goddard Space Flight Ctr. (United States)
Yang Soong, NASA Goddard Space Flight Ctr. (United States)
Takanori Izumiya, Chuo Univ. (Japan)
Sari Minami, Nara Women's Univ. (Japan)


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