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

Time assignment system and its performance aboard the Hitomi satellite
Author(s): Yukikatsu Terada; Sunao Yamaguchi; Shigenobu Sugimoto; Taku Inoue; Souhei Nakaya; Maika Murakami; Seiya Yabe; Kenya Oshimizu; Mina Ogawa; Tadayasu Dotani; Yoshitaka Ishisaki; Kazuyo Mizushima; Takashi Kominato; Hiroaki Mine; Hiroki Hihara; Kaori Iwase; Tomomi Kouzu; Makoto S. Tashiro; Chikara Natsukari; Masanobu Ozaki; Motohide Kokubun; Tadayuki Takahashi; Satoko Kawakami; Masaru Kasahara; Susumu Kumagai; Lorella Angelini; Michael Witthoeft

Paper Abstract

Fast timing capability in x-ray observation of astrophysical objects is one of the key properties for the ASTRO-H (Hitomi) mission. Absolute timing accuracies of 350 or 35    μ s are required to achieve nominal scientific goals or to study fast variabilities of specific sources. The satellite carries a GPS receiver to obtain accurate time information, which is distributed from the central onboard computer through the large and complex SpaceWire network. The details of the time system on the hardware and software design are described. In the distribution of the time information, the propagation delays and jitters affect the timing accuracy. Six other items identified within the timing system will also contribute to absolute time error. These error items have been measured and checked on ground to ensure the time error budgets meet the mission requirements. The overall timing performance in combination with hardware performance, software algorithm, and the orbital determination accuracies, etc. under nominal conditions satisfies the mission requirements of 35    μ s . This work demonstrates key points for space-use instruments in hardware and software designs and calibration measurements for fine timing accuracy on the order of microseconds for midsized satellites using the SpaceWire (IEEE1355) network.

Paper Details

Date Published: 29 December 2017
PDF: 10 pages
J. Astron. Telesc. Instrum. Syst. 4(1) 011206 doi: 10.1117/1.JATIS.4.1.011206
Published in: Journal of Astronomical Telescopes, Instruments, and Systems Volume 4, Issue 1
Show Author Affiliations
Yukikatsu Terada, Saitama Univ. (Japan)
Sunao Yamaguchi, Saitama Univ. (Japan)
Shigenobu Sugimoto, Saitama Univ. (Japan)
Taku Inoue, Saitama Univ. (Japan)
Souhei Nakaya, Saitama Univ. (Japan)
Maika Murakami, Saitama Univ. (Japan)
Seiya Yabe, Saitama Univ. (Japan)
Kenya Oshimizu, Saitama Univ. (Japan)
Mina Ogawa, Institute of Space and Astronautical Science (Japan)
Japan Aerospace Exploration Agency (Japan)
Tadayasu Dotani, Institute of Space and Astronautical Science (Japan)
Japan Aerospace Exploration Agency (Japan)
Yoshitaka Ishisaki, Tokyo Metropolitan Univ. (Japan)
Kazuyo Mizushima, NEC Corp. (Japan)
Takashi Kominato, NEC Corp. (Japan)
Hiroaki Mine, NEC Corp. (Japan)
Hiroki Hihara, NEC Corp. (Japan)
NEC Space Technologies Ltd. (Japan)
Kaori Iwase, Saitama Univ. (Japan)
Tomomi Kouzu, Saitama Univ. (Japan)
NEC Space Technologies Ltd. (Japan)
Makoto S. Tashiro, Saitama Univ. (Japan)
Institute of Space and Astronautical Science (Japan)
Japan Aerospace Exploration Agency (Japan)
Chikara Natsukari, Institute of Space and Astronautical Science (Japan)
Japan Aerospace Exploration Agency (Japan)
Masanobu Ozaki, Japan Aerospace Exploration Agency (Japan)
Institute of Space and Astronautical Science (Japan)
Motohide Kokubun, Institute of Space and Astronautical Science (Japan)
Japan Aerospace Exploration Agency (Japan)
Tadayuki Takahashi, Institute of Space and Astronautical Science (Japan)
Japan Aerospace Exploration Agency (Japan)
Satoko Kawakami, NEC Space Technologies Ltd. (Japan)
Masaru Kasahara, NEC Space Technologies Ltd. (Japan)
Susumu Kumagai, NEC Space Technologies Ltd. (Japan)
Lorella Angelini, NASA Goddard Space Flight Ctr. (United States)
Michael Witthoeft, NASA Goddard Space Flight Ctr. (United States)
ADNET Systems, Inc. (United States)


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