//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29543 SUBJECT: GRB 210222A: MAXI/GSC detection DATE: 21/02/22 20:18:01 GMT FROM: Motoko Serino at RIKEN/MAXI M. Nakajima (Nihon U.), M. Serino (AGU), Y. Kawakubo (LSU), H. Negoro, M. Aoki, K. Kobayashi, R. Takagi, K. Asakura, K. Seino (Nihon U.), T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Nishida, K. Komachi, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, R. Adachi, M. Niwano, R. Hosokawa (Tokyo Tech), S. Nakahira, Y. Sugawara, 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 (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (UDP/NAOJ), K. Yamaoka (Nagoya U.), M. Sugizaki (NAOC) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 2021-02-22T15:59:19 UT. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (353.129 deg, -29.464 deg) = (23 32 30, -29 27 50) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.11 deg and 0.04 deg, respectively. The roll angle of long axis from the north direction is 90.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 389 +- 38 mCrab (4.0-10.0keV, 1 sigma error). There was no significant excess flux in the previous transit at 14:26 UT with an upper limit of 20 mCrab. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29544 SUBJECT: Swift GRB210222.94: Global MASTER-Net observations report DATE: 21/02/22 22:56:30 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, 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, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB210222.94 (trigger No 1034325,10h 18m 29.04s , -14d 53m 52.8s, R=0.05) errorbox 235 sec after notice time and 276 sec after trigger time at 2021-02-22 22:42:03 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 17 deg. The sun altitude is -48.0 deg. The galactic latitude b = 34 deg., longitude l = 258 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1553237 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 367 | MASTER-SAAO | C | 180 | 17.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29553 SUBJECT: GRB 210222A: CALET Gamma-Ray Burst Monitor detection DATE: 21/02/23 10:08:53 GMT FROM: Valentin Pal'shin at AGU P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), and the CALET collaboration: At 15:57:23.469 UTC on 22 February 2021, the CALET Gamma-ray Burst Monitor (CGBM) triggered on long GRB 210222A (http://cgbm.calet.jp/cgbm_trigger/flight/1298044600/), which was also detected by the MAXI/GSC at T0(CGBM)+116 s (Nakajima et al., GCN Circ. 29543). The burst signal was seen by all CGBM detectors. The burst light curve shows a FRED-like pulse which starts at T+0.6 sec, peaks at T+7.5 sec, and ends at T+87.3 sec. The T90 and T50 durations measured by the SGM data are 71.4 +- 11.5 sec and 33.5 +- 4.4 sec (40-1000 keV), respectively. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1298044600/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29564 SUBJECT: Konus-Wind detection of GRB 210222A DATE: 21/02/24 15:02:52 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, A.Lysenko, D. Svinkin, A. Ridnaya, A. Tsvetkova, M. Ulanov, and T. Cline, report: The long GRB 210222A (MAXI/GSC detection: Nakajima et al., GCN 29543; CALET Gamma-Ray Burst Monitor detection: Marrocchesi et al., GCN 29553) was detected by Konus-Wind (KW) in the waiting mode starting from ~T0 = 57443.990 (15:57:23.990) UT (or ~2 minutes before the MAXI trigger). A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band reveals a ~30 sigma count rate increase over background in the interval from ~T0 to ~T0+177 s. The KW light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB210222A/ Modeling the KW 3-channel time-integrated spectrum (measured from T0+0.115 s to T0+176.755 s) by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.33(-0.11,+0.15) and Ep = 317(-72,+108) keV. A CPL fit to the spectrum near the peak count rate, measured from T0+0.115 s to T0+14.835 s, gives alpha -0.48(-0.14,+0.15), and Ep of 375(-40,+40) keV. In the 10 keV -10 MeV band, the total burst fluence is (4.2 ± 0.6)x10^-5 erg/cm^2, and the 2.944 s peak energy flux is (9.3 ± 0.8)x10^-7 erg/cm^2. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary.