Kavli Affiliate: Eric D. Miller
| First 5 Authors: Megumi Shidatsu, Yukikatsu Terada, Takashi Kominato, So Kato, Ryohei Sato
| Summary:
We report the results from the ground and on-orbit verifications of the XRISM
timing system when the satellite clock is not synchronized to the GPS time. In
this case, the time is determined by a free-run quartz oscillator of the clock,
whose frequency changes depending on its temperature. In the thermal vacuum
test performed in 2022, we obtained the GPS unsynchronized mode data and the
temperature-versus-clock frequency trend. Comparing the time values calculated
from the data and the true GPS times when the data were obtained, we confirmed
that the requirement (within a 350 $mu$s error in the absolute time,
accounting for both the spacecraft bus system and the ground system) was
satisfied in the temperature conditions of the thermal vacuum test. We also
simulated the variation of the timing accuracy in the on-orbit temperature
conditions using the Hitomi on-orbit temperature data and found that the error
remained within the requirement over $sim 3 times 10^{5}$ s. The on-orbit
tests were conducted in 2023 September and October as part of the bus system
checkout. The temperature versus clock frequency trend remained unchanged from
that obtained in the thermal vacuum test and the observed time drift was
consistent with that expected from the trend.
| Search Query: ArXiv Query: search_query=au:”Eric D. Miller”&id_list=&start=0&max_results=3