{
  "bibcode": "2025GCN.41600....1U",
  "body": "T. Usuki (Ehime U.), M. Nakajima, H. Negoro (Nihon U.), M. Serino (AGU),\nK. Takagi, H. Takahashi, H. Nishio  (Nihon U.), \nT. Mihara, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), \nT. Sakamoto, S. Sugita, Y. Kawakubo, H. Hiramatsu, Y. Kondo, A. Yoshida (AGU), \nY. Tsuboi, H. Sugai, N. Nagashima, Y. Ishihara (Chuo U.), \nM. Shidatsu, C. Kang, T. Nakamoto (Ehime U.),\nI. Takahashi, Y. Yatsu (Science Tokyo), \nS. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), \nY. Ueda, K. Fujiwara (Kyoto U.), \nM. Yamauchi, M. Nishio, C. Hiraizumi (Miyazaki U.), \nK. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.),\nT. Kawamuro (Osaka U.), S. Yamada (Tohoku U),\nreport on behalf of the MAXI team:\n\nThe MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source \nat 00:53:04 UT on August 30, 2025.\nAssuming that the source flux was constant over the transit,\nwe obtain the source position at\n(R.A., Dec) = (133.397 deg, 33.778 deg) = (08 53 35, +33 46 40) (J2000)\nwith a statistical 90% C.L. elliptical error region\nwith long and short radii of 0.26 deg and 0.26 deg, respectively.\nThe roll angle of the long axis from the north direction is 34.0 deg counterclockwise.\nThere is an additional systematic uncertainty of 0.1 deg (90% containment radius).\nThe X-ray flux averaged over the scan was 182 +- 40 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) = (132.876, 34.855) deg = (08 51 30, +34 51 17) (J2000)\n(R.A., Dec) = (132.372, 34.578) deg = (08 49 29, +34 34 40) (J2000)\n(R.A., Dec) = (133.708, 32.906) deg = (08 54 49, +32 54 21) (J2000)\n(R.A., Dec) = (134.206, 33.177) deg = (08 56 49, +33 10 37) (J2000)\nThere was no significant excess flux in the previous transit at August 29 23:20 UT\nand in the next transit at August 30 02:26 UT with an upper limit of 20 mCrab for each.\n\nWe tantatively name the source MAXI J0853+337, although we called it \nMAXI J0853+338 in MAXI new-transient ML.",
  "createdOn": 1756526204011,
  "format": "text/plain",
  "submitter": "Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>",
  "submittedHow": "web",
  "eventId": "GRB 250830A",
  "subject": "GRB 250830A / MAXI J0853+337: MAXI/GSC detection",
  "circularId": 41600
}