Evaluation of the initial pointing accuracy of XRISM

We report the first evaluation of the pointing accuracy of XRISM. It carries two X-ray telescopes, three star trackers (STTs), and two inertial reference units (IRUs). The attitude of the satellite is updated when at least two STTs are activated. Otherwise, IRUs keep it. The pointing accuracy is affected by the relative position of these devices, thermal conditions, and aberration. Therefore, it depends on several conditions such as the STT selection, the direction of the Sun, and the orbital movement. The fluctuation of attitude results in a change of the focal positions on the detector planes and the blur of the reconstructed image. We evaluated the trend from observations with different sun directions and STT combinations. The focal position on the microcalorimeter array was also validated.