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 \pm 0.08 \times 10 ^ { -8 } erg s ^ { -1 } cm ^ { -2 } with a 1 \sigma statistical uncertainty ) but is softer in the power-law index ( 2.19 \pm 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 .