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The X-ray Imaging and Spectroscopy Mission (XRISM) is an X-ray astronomy satellite successfully launched in September 2023. The satellite carries two X-ray telescopes with a focal length of 5.6 meters. One of these is Resolve, which consists of an X-ray Mirror Assembly (XMA) and a microcalorimeter array, providing a relatively narrow field of view (FoV) of 3.05 arcminutes squared. The other is Xtend, which consists of an XMA and an X-ray CCD camera, offering a large FoV of 38 arcminutes squared. Due to Resolve’s limited FoV, pointing accuracy is crucial for stable observation. The observation aimpoint, defined as the position on the focal plane where an on-axis target is located, was verified within a few arcseconds of the center of the array after the satellite’s boresight correction. It was also confirmed to be suitable, with no significant irreversible shift detected over approximately half a year. In the commissioning phase, all measurable requirements for pointing accuracy were confirmed to be met. The absolute pointing determination accuracies are less than 20 arcseconds for both instruments. The aimpoint shift and its temperature dependence were also assessed for each detector. The aimpoint shifts of both instruments in each observation have a good correlation on the X-axis, but not on the Y-axis in the detector coordinates. Resolve’s Y-axis shift clearly depends on the base panel temperature, on the order of a few arcseconds, which can be ignored for the absolute control accuracy and effective area. The sharp PSF core with an FWHM of approximately 10 arcseconds and arcsecond-scale relative determination accuracy enable Xtend to achieve good image reconstruction performance.
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