XRISM follow-up observation of the black hole X-ray binary GS 1354-64

ATel #17625; H. Liu (U. Tuebingen), T. Yoneyama, K. Fukushima, Y. Kanemaru, S. Ogawa, Y. Uchida (ISAS/JAXA), C. Baluta (NASA/GSFC), Y. Terada (Satama U.), E. Costantini (SRON), M. Guainazzi (ESA/ESTEC), R. Kelley (NASA/GSFC), K. Matsushita (TUS), R. Petre, B. Williams (NASA/GSFC), H. Yamaguchi, S. Watanabe (JAXA/ISAS), M. Tashiro (Saitama U.)
on 24 Jan 2026; 03:07 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)

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MAXI/GSC found a new outburst of the black hole X-ray binary GS 1354-64 on 2025-12-25 (ATel #17563). Since then, multi-wavelength follow-up observations have been carried out (ATel #17582, #17583, #17586, #17611, #17612, #17618). X-Ray Imaging and Spectroscopy Mission (XRISM) observed GS 1354-64 as a DDT target of opportunity. The observation started at 2026-01-20T03:37:00 and completed at 2026-01-23T04:00:00 (TT). The quick-look data of Resolve obtained from a slice of the observation, 2026-01-20T07:29:22 to 2026-01-21T05:36:09, yielded the X-ray flux of 5.3 × 10^-9 erg s^-1cm^-2 (2.0 – 13.0 keV). The preliminary source position is obtained to be (R.A., Dec.) = (209.542, -64.734) from the Xtend data in the same duration.