XRISM/Xtend Transient Search (XTS) detected a flux increase of XRISM J1236-6432
ATel #17232; T. Kiyomoto (Saitama U.), K. Fukushima, Y. Kanemaru, S. Ogawa (JAXA), M. Audard (U. de Geneve), E. Behar (Technion), T. Hakamata (Osaka U.), S. Inoue (Kyoto 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. Terada (Saitama U.), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), T. Yoneyama (Chuo U.), M. Yoshimoto (Ehime U.), J. SOKOLOSKI (Columbia U.)
on 16 Jun 2025; 15:40 UT
Credential Certification: Marina Yoshimoto (marinayoshimoto5@gmail.com)
Subjects: X-ray, Transient
XRISM/Xtend Transient Search (XTS) detected a gradual increase in the flux of the X-ray source XRISM J1236-6432 from 2025-6-12 to 2025-6-13 TT. The source position is determined to be (R.A., Dec.) = (188.884, -64.528), with a systematic error of ∼ 40 arcsec. A plausible counterpart is the 4XMM J123530.3-643125, which is located ∼ 20 arcsec apart from the position of XRISM J1236-6432. All statistical uncertainties in this report are provided as a 90% confidence level unless stated otherwise.
In the duration of ∼ 80 ks, the flux increased several times. The average flux is calculated as 5 × 10-13 erg s-1 cm-2 (0.4 – 10.0 keV), using an absorbed power-law model. This result is one order of magnitude greater than the catalog flux of the 4XMM J123530.3-643125. The photon index and column density are derived as 1 and < 3 × 1020 cm-2, respectively.
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 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.
