The time assignment system of ASTRO-H

Kouzu, Tomomi; Iwase, Kaori; Mishima, Yuki; Terada, Y.; Yuasa, Takayuki; Ishisaki, Yoshitaka; Tashiro, M.; Kokubun, M.; Nomachi, M.; Takahashi, Tadayuki

doi:10.1109/nssmic.2011.6154471

Cited by 1 publication

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“…5 However, fast timing capability is also a key performance requirement for understanding variable astrophysical objects in the X-ray band. According to typical time scales for variation in various X-ray sources, 6 an absolute timing accuracy of 350 µs covers most (but not all) of the scientific requirements for the Hitomi mission, and is achievable with conventional methods, as demonstrated by the previous X-ray mission Suzaku. 7 Therefore, scientific requirements for the Hitomi timing system are defined as an absolute accuracy of 350 µs, a value that should be achieved even following a single-point on-orbit failure.…”

Section: Timing Capability For the Hitomi Satellitementioning

confidence: 99%

Time assignment system and its performance aboard the Hitomi satellite

Terada

Yamaguchi

Sugimoto

et al. 2017

J. Astron. Telesc. Instrum. Syst.

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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 µs 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 on 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 35µs. 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.

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Section: Timing Capability For the Hitomi Satellitementioning

confidence: 99%