Spectroscopic Performance of XRISM’s Resolve Instrument

The Resolve X-ray spectrometer is an instrument aboard the XRISM observatory that was launched into low-Earth orbit on September 7, 2023 JST. Resolve is a low-temperature (50 mK), non-dispersive, X-ray spectrometer incorporating a 36-pixel microcalorimeter array with spectral resolution better than 5 eV full-width at half-maximum at 6 keV for point sources and extended objects alike. An anti-coincidence detector located behind the spectroscopy array provides effective background rejection. In this presentation, we discuss the in-orbit performance, including spectral resolution, absolute energy knowledge, instrument background, and stability. We will also present other important results from the commissioning phase and in-flight calibration accomplished so far. We will explain the instrumental effects behind time-dependent energy-scale corrections and routine event screening, and we will discuss any special cases that may require modified processing.