XRISM follow-up observation of the Be X-ray binary 1A 1118-61
ATel #17667; T. Takagi (Ehime U.), C. Diez (ESA/ESAC), S. Dupourqué (IRAP), G. Matzeu (ESA/ESAC), 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 11 Feb 2026; 06:10 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
Swift/BAT triggered a new outburst of the Be X-ray binary 1A 1118-61 on 2026-01-18 (ATel #17608). Since then, X-ray and optical follow-up observations have been carried out (ATel #17613, #17616, #17620, #17626, #17627).
X-Ray Imaging and Spectroscopy Mission (XRISM) observed 1A 1118-61 as a target of opportunity using the director's discretionary time. The observation was from 2026-02-07T00:19:00 to 2026-02-07T19:45:00 (TT). The quick-look data of Resolve obtained from a slice of the observation, 2026-02-07T17:35:39 to 2026-02-07T19:25:10, yielded the X-ray flux of 2.64 × 10-9 erg s-1cm-2 (2.0 – 13.0 keV). The preliminary source position is obtained to be (R.A., Dec.) = (170.235, -61.917) from the Xtend data in the same duration.
