XRISM/Xtend Transient Search (XTS) detected an X-ray flare possibly from EXO 092202-6244.9
ATel #17536; M. Yoshimoto (Ehime U.), H. Takahashi (Hiroshima U.), K. Fukushima, Y. Kanemaru, S. Ogawa, Y. Uchida, T. Yoneyama (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), T. Hakamata (UOsaka), S. Inoue (Kyoto U.), Y. Ishihara (Chuo U.), C. Kang (Ehime U.), T. Kiyomoto (Saitama U.), T. Kohmura (TUS), H. Kuramoto (UOsaka), J. Kurashima (U. of Miyazaki), Y. Maeda (JAXA), H. Matsumoto (UOsaka), T. Matsushima (U. of Miyazaki), A. Miyamoto (UOsaka), M. Mizumoto (UTEF), K. Mori (U. of Miyazaki), Y. Motogami (Saitama U.), N. Nagashima (Chuo U.), T. Narita (Kyoto U.), M. Nobukawa (NUE), H. Noda (Tohoku U.), Y. Sakamoto (Tohoku U.), M. Shidatsu (Ehime U.), H. Sugai (Chuo U.), T. Takagi (Ehime U.), S. Takatsuka (UOsaka), R. Takemoto (U. of Miyazaki), Y. Terada (Saitama U., JAXA), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), A. Yoshimoto (NWU)
on 10 Dec 2025; 12:41 UT
Credential Certification: Tomokage Yoneyama (tyoneyama263@g.chuo-u.ac.jp)
Subjects: X-ray, Transient
XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J0923-6258 on 2025-12-08 TT. The source position is determined to be (R.A., Dec.) = (140.824,-62.964), with a systematic error of ∼ 40 arcsec. The plausible counterpart is an X-ray source EXO 092202-6244.9, located ∼ 32 arcsec apart from the position of XRISM J0923-6258.Two optical counterpart candidates, TYC 8944-2554-1 and UCAC4 136-022073, are located ∼ 22 and 34 arcsec apart, respectively.
The flare occurred on 2025-12-08 at ∼ 14:32 and reached its peak at 16:20 with the flux of 8 ×
10-12 erg s-1cm-2 (0.4 – 10.0 keV). The flare exponentially decayed in 5 × 103 sec.
We estimated the systematic error for the source position from the separations between the detected sources with the
corresponding counterparts in the same field of view.
