//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31303 SUBJECT: GRB 211225A/MAXI J0827-071: MAXI/GSC detection DATE: 21/12/25 05:14:45 GMT FROM: Hitoshi Negoro at Nihon U T. Kurihara (JAXA), H. Negoro, M. Nakajima, K. Kobayashi, K. Asakura, K. Seino (Nihon U.), T. Mihara, T. Tamagawa, J. Li, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, K. Komachi, H. Hiramatsu, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.), M. Shidatsu, M. Iwasaki (Ehime U.), N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA), Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, Y. Goto, R. Uematsu, K. Inaba (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, Y. Nonaka, T. Sato, R. Hatsuda, R. Fukuoka (Miyazaki U.), T. Kawamuro (UDP/NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source at 03:22:28 UT on 2021 December 25. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (126.923 deg, -7.182 deg) = (08 27 41, -07 10 55) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.20 deg and 0.17 deg, respectively. The roll angle of long axis from the north direction is 40.0 deg counterclockwise. Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners: (R.A., Dec) = (126.189, -7.957) deg = (08 24 45, -07 57 25) (J2000) (R.A., Dec) = (126.475, -8.145) deg = (08 25 53, -08 08 41) (J2000) (R.A., Dec) = (127.569, -6.507) deg = (08 30 16, -06 30 25) (J2000) (R.A., Dec) = (127.284, -6.319) deg = (08 29 08, -06 19 08) (J2000) The X-ray flux averaged over the scan was 203 +- 29 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 01:49 UT with an upper limit of 20 mCrab. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31304 SUBJECT: MAXI GRB211225.14: Global MASTER-Net observations report DATE: 21/12/25 05:34:06 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina, A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez, M.L.H.Rodriguez (INAOE, OAGH) A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) started inspect of the MAXI GRB211225.14 (trigger No 573117444,08h 27m 42.24s , -07d 10m 37.2s, R=1) errorbox 1254 sec after notice time and 5558 sec after trigger time at 2021-12-25 04:55:16 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 43 deg. The sun altitude is -37.9 deg. The galactic latitude b = 18 deg., longitude l = 231 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1826591 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 5649 | 2021-12-25 04:55:16 | MASTER-IAC | (08h 25m 29.91s , -07d 05m 23.5s) | P| | 180 | 17.9 | 5649 | 2021-12-25 04:55:16 | MASTER-IAC | (08h 26m 26.13s , -07d 11m 22.7s) | P- | 180 | 17.4 | The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31310 SUBJECT: GRB 211225A: MITSuME Akeno optical upper limits DATE: 21/12/26 13:16:55 GMT FROM: Naohiro Ito at Tokyo Tech N. Ito, R. Hosokawa, M. Niwano, K. L. Murata, Y. Imai, Y. Takamatsu, R. Yamaguchi, R. Noto, S. Sato, M. Takaku, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We performed tiling observations for the MAXI/GSC error region of GRB 211225A, MAXI J0827-071 (T. Kurihara et al. GCN Circular #31303, V. Lipunov et al. GCN Circular #31304) with an optical tri-color (g', Rc, and Ic) camera attached to the MITSuME 50 cm telescope Akeno. The follow up observation started at 2021-12-25 12:43:40 UT, 9.4 hours after the trigger. Our tiling observation covered almost ~90% of the MAXI/GSC elliptical error region (GCN Circular #31303). Comparing our co-added images with the GSC2.3 catalog, we found no optical transients in the observed region. The 5-sigma upper limits of the co-added images are listed below. Field num. | center position (R.A., Dec.) | size of field (R.A.(arcmin) x Dec.(arcmin)) | 5-sigma upper limit | MID-UT (UT) | exposure time (sec) -------------------------------------------------------------------------------------------------------------------------- Field 00 | 8:27:04, -7:19:28 | 25.1 x 24.8 | g'>18.1, Rc>18.4, Ic>17.9 | 2021-12-25 15:30:02 | 1260 Field 01 | 8:28:39, -7:19:27 | 26.1 x 25.1 | g'>18.1, Rc>18.4, Ic>17.6 | 2021-12-25 15:36:28 | 1380 Field 02 | 8:27:01, -6:54:21 | 26.3 x 24.0 | g'>18.3, Rc>18.7 | 2021-12-25 16:31:42 | 2400 Field 03 | 8:28:37, -6:54:57 | 26.3 x 24.6 | g'>18.0, Rc>18.4, Ic>17.8 | 2021-12-25 16:48:59 | 1620 -------------------------------------------------------------------------------------------------------------------------- We used PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).