XRISM/Xtend Transient Search (XTS) detected an X-ray flare from XRISM J1235-6432

ATel #17231; T. Kiyomoto, Y. Terada (Saitama U.), S. Inoue, H. Uchida (Kyoto U.), K. Fukushima, Y. Kanemaru, S. Ogawa (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), T. Hakamata (Osaka U.), Y. Ishihara (Chuo U.), C. Kang (Ehime U.), T. Kohmura (TUS), H. Kuramoto (Osaka U.), J. Kurashima (U. of Miyazaki), Y. Maeda (JAXA), H. Matsumoto (Osaka U.), T. Matsushima (U. of Miyazaki), A. Miyamoto (Osaka U.), 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.), K. Pottschmidt (UMBC, NASA GSFC, CRESST), Y. Sakamoto (Tohoku U.), M. Shidatsu (Ehime U.), H. Sugai (Chuo U.), H. Takahashi (Hiroshima U.), T. Takagi (Ehime U.), S. Takatuska (Osaka U.), R. Takemoto (U. of Miyazaki), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), T. Yoneyama (Chuo U.), M. Yoshimoto (Ehime U.), J. SOKOLOSKI (Columbia U.)
on 16 Jun 2025; 14:48 UT
Credential Certification: Yukikatsu Terada (terada@mail.saitama-u.ac.jp)

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XRISM/Xtend Transient Search (XTS) detected two flare phenomena from the X-ray source XRISM J1235-6432 from 2025-6-12 to 2025-6-13 TT. The source position is determined to be (R.A., Dec.) = (188.793, -64.535), with a systematic error of ∼ 40 arcsec. A plausible counterpart is the 1eRASS J123508.6-643153 or 4XMM J123508.4-643149 or 2CXO J123508.5-643148, which are located ∼ 16 arcsec, 20 arcsec, or 20 arcsec apart from the position of XRISM J1235-6432, respectively. All statistical uncertainties in this report are provided at a confidence level of 90% unless otherwise stated.

XRISM/XTS detected the two flares, one from 2025-06-12T10:02:58 with a duration of ∼ 7,000 sec and another from 2025-06-13T10:31:19 with a duration of ∼ 5,000 sec. The peak flux is calculated as 2 × 10^-13 erg s^-1 cm^-2 (0.4 – 2.0 keV) and 1 × 10^-13 erg s^-1 cm^-2 (0.4 – 2.0 keV) for the first and second flares, respectively. A systematic error of roughly 20% should be added to the statistical error.

We derived the above systematic error for the flux by comparing our derived values for the sources detected with XTS in several observations with those for the corresponding X-ray counterparts. We estimate the systematic error for the position of the source from the separations between the detected sources with the corresponding counterparts in the same field of view.