  Xtend is one of the two telescopes onboard the X-ray imaging and spectroscopy
mission (XRISM), which was launched on September 7th, 2023. Xtend comprises the
Soft X-ray Imager (SXI), an X-ray CCD camera, and the X-ray Mirror Assembly
(XMA), a thin-foil-nested conically approximated Wolter-I optics. A large field
of view of $38^{\prime}\times38^{\prime}$ over the energy range from 0.4 to 13
keV is realized by the combination of the SXI and XMA with a focal length of
5.6 m. The SXI employs four P-channel, back-illuminated type CCDs with a thick
depletion layer of 200 $\mu$m. The four CCD chips are arranged in a 2$\times$2
grid and cooled down to $-110$ $^{\circ}$C with a single-stage Stirling cooler.
Before the launch of XRISM, we conducted a month-long spacecraft thermal vacuum
test. The performance verification of the SXI was successfully carried out in a
course of multiple thermal cycles of the spacecraft. About a month after the
launch of XRISM, the SXI was carefully activated and the soundness of its
functionality was checked by a step-by-step process. Commissioning observations
followed the initial operation. We here present pre- and post-launch results
verifying the Xtend performance. All the in-orbit performances are consistent
with those measured on ground and satisfy the mission requirement. Extensive
calibration studies are ongoing.
