//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13346 SUBJECT: GRB 120528B: MAXI/GSC detection DATE: 12/05/29 01:41:48 GMT FROM: Nobuyuki Kawai at Tokyo Tech M. Morii, N. Kawai, R. Usui, K. Ishikawa (Tokyo Tech), M. Serino, T. Mihara, M. Sugizaki, T. Yamamoto, M. Matsuoka (RIKEN), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa (JAXA), H. Negoro, M. Nakajima, N. Serita, M. Asada, H. Sakakibara (Nihon U.), A. Yoshida (AGU), H. Tsunemi, M. Kimura (Osaka U.), Y. Ueda, K. Hiroi, M. Shidatsu, R. Sato (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.) M. Yamauchi, Y. Nishimura, T. Hanayama, K. Yoshidome (Miyazaki U.), K. Yamaoka (Waseda U.) report on behalf of the MAXI team: MAXI/GSC triggered at 2012-05-28T18:12:08 UT on a bright uncatalogued X-ray transient source. The transient emission lasted at least for 20.0 seconds within the 40.0 second long triangular transit response of MAXI/GSC. We identify this event as GRB 120528B. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (+77.59 deg, -37.80 deg) = (05 10 21, -37 47 50)(J2000) with a rectangular statistical error box (90%C.L.) of the following corners: (R.A., Dec) = (+77.23 deg, -37.92 deg) = (05 08 56, -37 54 60)(J2000) (R.A., Dec) = (+77.56 deg, -38.12 deg) = (05 10 16, -38 07 15)(J2000) (R.A., Dec) = (+77.96 deg, -37.71 deg) = (05 11 51, -37 42 47)(J2000) (R.A., Dec) = (+77.63 deg, -37.51 deg) = (05 10 31, -37 30 36)(J2000) There is an additional systematic uncertainty of 0.1 deg (90% containment radius). Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners: (R.A., Dec) = (+76.80 deg, -37.54 deg) = (05 07 12, -37 32 34)(J2000) (R.A., Dec) = (+77.09 deg, -37.25 deg) = (05 08 21, -37 15 0)(J2000) (R.A., Dec) = (+78.38 deg, -38.05 deg) = (05 13 31, -38 02 57)(J2000) (R.A., Dec) = (+78.09 deg, -38.35 deg) = (05 12 22, -38 20 42)(J2000) The X-ray flux averaged over the scan was 285 +65/-58 mCrab (4-10 keV, 1 sigma error). Follow-up observations are encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13351 SUBJECT: Konus-Wind observation of GRB 120528B DATE: 12/05/31 10:25:04 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team report: The long GRB 120528B (MAXI/GSC detection and localization: M. Morii et al., GCN 13346) was detected by Konus-Wind in the waiting mode starting at T0(KW)= 65508 s UT (18:11:48), ~20s before the T0(MAXI). The burst light curve shows a single pulse with a total duration of ~30s. As observed by Konus-Wind, the burst had a fluence of (2.9 ± 0.8)x10-6 erg/cm2 (in the 20 - 1200 keV energy range). Modelling the K-W 3-channel time-integrated spectrum (from T0(KW) to T0(KW)+26 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -0.41 ± 1.22, and Ep = 201 ± 112 keV All the quoted errors are estimated at the 1 sigma confidence level. The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB120528B/