We present the result of the in-flight calibration of the effective area of the Soft X-ray Spectrometer (SXS) onboard the Hitomi X-ray satellite using an observation of the Crab nebula. We corrected for the artifacts when observing high count rate sources with the X-ray microcalorimeter. We then constructed a spectrum in the 0.5-20 keV band, which we modeled with a single power-law continuum attenuated by an interstellar extinction. We evaluated the systematic uncertainty upon the spectral parameters by various calibration items. In the 2-12 keV band, the SXS result is consistent with the literature values in flux (2.20 ± 0.08) ×10−8 erg s−1 cm−2 with a 1σ statistical uncertainty) but is softer in the power-law index (2.19 ± 0.11). The discrepancy is attributable to the systematic uncertainty of about +6/−7% and +2/−5% respectively for the flux and the power-law index. The softer spectrum is affected primarily by the systematic uncertainty of the Dewar gate valve transmission and the event screening.
@article{arxiv.1801.02104,
title = {In-flight Calibration of Hitomi Soft X-ray Spectrometer (3) Effective Area},
author = {Masahiro Tsujimoto and Takashi Okajima and Megan E. Eckart and Takayuki Hayashi and Akio Hoshino and Ryo Iizuka and Richard L. Kelley and Caroline A. Kilbourne and Maurice A. Leutenegger and Yoshitomo Maeda and Hideyuki Mori and Frederick S. Porter and Kosuke Sato and Toshiki Sato and Peter J. Serlemitsos and Andrew Szymkowiak and Tahir Yaqoob},
journal= {arXiv preprint arXiv:1801.02104},
year = {2018}
}