Time assignment system and its performance aboard the Hitomi satellite

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

doi:10.1117/1.JATIS.4.1.011206

29 December 2017 Time assignment system and its performance aboard the Hitomi satellite

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

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Journal of Astronomical Telescopes, Instruments, and Systems, Vol. 4, Issue 1, 011206 (December 2017). https://doi.org/10.1117/1.JATIS.4.1.011206

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 μs 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 μs. 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.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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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, and Michael Witthoeft "Time assignment system and its performance aboard the Hitomi satellite," Journal of Astronomical Telescopes, Instruments, and Systems 4(1), 011206 (29 December 2017). https://doi.org/10.1117/1.JATIS.4.1.011206

Received: 14 July 2017; Accepted: 4 December 2017; Published: 29 December 2017

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