How large is the difference in the pointing
direction between XIS and HXD?
Although the average optical axis of XIS and that of HXD-PIN differ by about
5 arcmin, the XIS field of view is entirely covered by the HXD-PIN field of
view. Users therefore always obtain both XIS and HXD data simultaneously.
Taking into account this difference, we prepared the two default pointing
positions, XIS nominal and HXD nominal positions, which prioritizes the
observation efficiency of XIS over that of HXD, and vice versa.