31 July 2014 ASTRO-H Soft X-ray Telescope (SXT)
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ASTRO-H is an astrophysics satellite dedicated for non-dispersive X-ray spectroscopic study on selective celestial X-ray sources. Among the onboard instruments there are four Wolter-I X-ray mirrors of their reflectors’ figure in conical approximation. Two of the four are soft X-ray mirrors1, of which the energy range is from a few hundred eV to 15 keV within the effective aperture being defined by the nested reflectors’ radius ranging between 5.8 cm to 22.5 cm. The focal point instruments will be a calorimeter (SXS) and a CCD camera (SXI), respectively. The mirrors were in quadrant configuration with photons being reflected consecutively in the primary and secondary stage before converging on the focal plane of 5.6 m away from the interface between the two stages. The reflectors of the mirror are made of heat-formed aluminum substrate of the thickness gauged of 152 μm, 229 μm, and 305 μm of the alloy 5052 H-19, followed by epoxy replication on gold-sputtered smooth Pyrex cylindrical mandrels to acquire the X-ray reflective surface. The epoxy layer is 10 m nominal and surface gold layer of 0.2 μm. Improvements on angular response over its predecessors, e.g. Astro-E1/Suzaku mirrors, come from error reduction on the figure, the roundness, and the grazing angle/radius mismatching of the reflecting surface, and tighter specs and mechanical strength on supporting structure to reduce the reflector positioning and the assembly errors. Each soft x-ray telescope (SXT), SXT-1 or SXT-2, were integrated from four independent quadrants of mirrors. The stray-light baffles, in quadrant configuration, were mounted onto the integrated mirror. Thermal control units were attached to the perimeter of the integrated mirror to keep the mirror within operating temperature in space. The completed instrument went through a series of optical alignment, thus made the quadrant images confocal and their optical axes in parallel to achieve highest throughput possible. Environmental tests were carried out, and optical quality of the telescopes has been confirmed. SXT-1 and -2 were tested with the broad but slightly divergent beam, up to 8 arc-minutes, at Goddard. The full characterization were carried out in Japan which includes: angular resolution, effective area in the energy range of ~ 0.4 – 12keV, off-axis response at various energies, etc. We report the calibration results of the SXT-1 and -2 that were obtained at NASA/Goddard and JAXA/ISAS. The detailed calibration are reported in the two papers in this conference: 9144-206, "Ground-based x-ray calibration of the ASTRO-H soft x-ray telescopes" by R. Iizuka et al. and 9144-207, "Revealing a detailed performance of the soft x-ray telescopes of the ASTRO-H mission" by T. Sato, et al. Some small but significant discrepancies existed between ISAS and Goddard measurements that were attributed to the difference of the X-ray beams - pencil beam vs divergent beam.
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Yang Soong, Yang Soong, Takashi Okajima, Takashi Okajima, Peter J. Serlemitsos, Peter J. Serlemitsos, Stephen L. Odell, Stephen L. Odell, Brian D. Ramsey, Brian D. Ramsey, Mikhail V. Gubarev, Mikhail V. Gubarev, Manabu Ishida, Manabu Ishida, Yoshitomo Maeda, Yoshitomo Maeda, Ryo Iizuka, Ryo Iizuka, Takayuki Hayashi, Takayuki Hayashi, Yuzuru Tawara, Yuzuru Tawara, Akihiro Furuzawa, Akihiro Furuzawa, Hideyuki Mori, Hideyuki Mori, Takuya Miyazawa, Takuya Miyazawa, Hideyo Kunieda, Hideyo Kunieda, Hisamitsu Awaki, Hisamitsu Awaki, Satoshi Sugita, Satoshi Sugita, Keisuke Tamura, Keisuke Tamura, Kazunori Ishibashi, Kazunori Ishibashi, Takanori Izumiya, Takanori Izumiya, Sari Minami, Sari Minami, Toshiki Sato, Toshiki Sato, Kazuki Tomikawa, Kazuki Tomikawa, Naomichi Kikuchi, Naomichi Kikuchi, Toshihiro Iwase, Toshihiro Iwase, } "ASTRO-H Soft X-ray Telescope (SXT)", Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 914428 (31 July 2014); doi: 10.1117/12.2056804; https://doi.org/10.1117/12.2056804


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