Xtend: XRISM’s Soft X-ray Imager

Xtend is one of the two telescopes onboard XRISM, comprising 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′ x 38′ over the energy range from 0.4 to 13 keV is realized by the combination of the SXI and XMA. The SXI employs four P-channel, back-illuminated type CCDs with a thick depletion layer of 200 um. The four CCD chips are arranged in a 2x2 grid and cooled down to -110° Celsius with a single-stage Stirling cooler. SXI performed its start-up operation 40 days after the launch of XRISM. During subsequent operations, the spectroscopic and imaging performances were confirmed to be as expected from the ground tests and satisfy the requirements placed on Xtend to achieve the scientific objectives of XRISM. Initial results of these start-up and verification operations and in-orbit calibration will be reported in this presentation.