{
  "createdOn": 1737893479555,
  "body": "Y. Okada (Kyoto U.), H. Negoro (Nihon U.), Y. Kawakubo (AGU), \nM. Nakajima, Y. Kudo, H. Shibui, K. Takagi, H. Takahashi, K. Tatano, H. Nishio (Nihon U.), \nT. Mihara, S. Yamada, S. Wang, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), \nT. Sakamoto, M. Serino, S. Sugita, H. Hiramatsu, H. Nishikawa, \nY. Kondo, S. Sasao, A. Yoshida (AGU), Y. Tsuboi, H. Sugai, N. Nagashima (Chuo U.), \nM. Shidatsu, Y. Niida (Ehime U.), I. Takahashi, M. Niwano, N. Higuchi, Y. Yatsu (Tokyo Tech), \nS. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), \nY. Ueda, K. Fujiwara (Kyoto U.), M. Yamauchi, Y. Otsuki, T. Hasegawa, M. Nishio (Miyazaki U.), \nK. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.), T. Kawamuro (Osaka U.), \nreport on behalf of the MAXI team:\n\nThe MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source,\nprobably GRB 250126A (GCN Circ. 39035, 39036), at 05:01:45 UT on January 26, 2025.\nAssuming that the source flux was constant over the transit, we obtain the source position at\n(R.A., Dec) = (337.621 deg, -14.383 deg) = (22 30 29, -14 22 58) (J2000) \nwith a statistical 90% C.L. elliptical error region \nwith long and short radii of 0.32 deg and 0.23 deg, respectively. \nThe roll angle of the long axis from the north direction is 50.0 deg counterclockwise. \nThere is an additional systematic uncertainty of 0.1 deg (90% containment radius).\nThe X-ray flux averaged over the scan was 148 +- 29 mCrab\n(4.0-10.0keV, 1 sigma error).\nWithout assumptions on the source constancy, we obtain a rectangular error\nbox for the transient source with the following corners:\n(R.A., Dec) = (337.049, -14.721) deg = (22 28 11, -14 43 15) (J2000)\n(R.A., Dec) = (337.415, -14.977) deg = (22 29 39, -14 58 37) (J2000)\n(R.A., Dec) = (338.598, -13.378) deg = (22 34 23, -13 22 40) (J2000)\n(R.A., Dec) = (338.233, -13.124) deg = (22 32 55, -13 07 26) (J2000)\nThere was no significant excess flux in the previous transit at 03:29 UT \nand in the next transit at 06:34 UT with an upper limit of 20 mCrab for each.\n",
  "circularId": 39038,
  "eventId": "GRB 250126A",
  "submittedHow": "web",
  "submitter": "Hitoshi Negoro at Nihon University/MAXI team <negoro.hitoshi@nihon-u.ac.jp>",
  "format": "text/plain",
  "subject": "GRB 250126A: MAXI/GSC detection",
  "bibcode": "2025GCN.39038....1O"
}