AGILE observations of the SGR 1935+2154 "burst forest"
ATel #13682; A. Ursi (INAF/IAPS), C. Pittori (SSDC and INAF/OAR), P. Tempesta (TeleSpazio), F. Verrecchia (SSDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), M. Cardillo, C. Casentini, G. Piano (INAF/IAPS), A. Bulgarelli, V. Fioretti, N. Parmiggiani (INAF/IASF-Bo), F. Lucarelli (SSDC and INAF/OAR), I. Donnarumma (ASI), S. Vercellone (INAF/OA-Brera), F. Gianotti, M. Trifoglio (INAF/IASF-Bo), A. Giuliani, S. Mereghetti, P. Caraveo, F. Perotti (INAF/IASF-Mi), A. Chen (Wits University), A. Argan, E. Costa, E. Del Monte, Y. Evangelista, M. Feroci, F. Lazzarotto, I. Lapshov, L. Pacciani, P. Soffitta, V. Vittorini (INAF/IAPS), G. Di Cocco, F. Fuschino, M. Galli, C. Labanti (INAF/IASF-Bo), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), A. Pellizzoni, M. Pilia, A. Trois (INAF/OA-Cagliari), G. Barbiellini, E. Vallazza (INFN Trieste), F. Longo (Univ. Trieste and INFN Trieste), A. Morselli, P. Picozza (INFN and Univ. Roma Tor Vergata), M. Prest (Univ. dell'Insubria), P. Lipari, D. Zanello (INFN and Univ. Roma Sapienza), P. W. Cattaneo, A. Rappoldi (INFN Pavia), A. Ferrari (Univ. Torino and CIFS), F. Paoletti (East Windsor RSD Hightstown and INAF/IAPS), A. Antonelli (INAF/OAR), P. Giommi, L. Salotti, G. Valentini, and F. D'Amico (ASI)
on 28 Apr 2020; 21:40 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Francesco Verrecchia (francesco.verrecchia@asdc.asi.it)
Subjects: X-ray, Gamma Ray, Request for Observations, Soft Gamma-ray Repeater, Transient
We report AGILE detection of several bursts from the Soft Gamma Repeater SGR 1935+2154, which were observed from T0 = 2020-04-27 18:32:59 (UT) until ~T0+7 hours. This burst activity was also detected by Swift/BAT (GCN #27657; Barthelmy et al.; ATel #13675; Palmer et al.), Fermi/GBM (GCN #27659; Fletcher et al.), MAXI/GSC (GCN #27661; Nakahira et al.), Insight-HXMT (GCN #27662; Lin et al.), CALET/CGBM (GCN #27663; Pal'shin et al.), AstroSat CZTI (GCN #27664; Bhalerao et al.), and NICER (ATel #13678; Younes et al.).
The bursts were clearly detected by the AGILE scientific ratemeters (RMs) of the SuperAGILE (18-60 keV) and Anti-Coincidence (50-200 keV) detectors.
The list of the main events is as follows:
1 UTC 2020-04-27 18:32:48
2 UTC 2020-04-27 18:33:10
3 UTC 2020-04-27 18:33:26
4 UTC 2020-04-27 18:33:31
5 UTC 2020-04-27 18:33:37
6 UTC 2020-04-27 18:34:11
7 UTC 2020-04-27 18:34:52
8 UTC 2020-04-27 18:49:33
9 UTC 2020-04-27 19:43:50
10 UTC 2020-04-27 20:14:57
11 UTC 2020-04-27 20:15:26
12 UTC 2020-04-27 20:22:01
13 UTC 2020-04-27 21:14:51
14 UTC 2020-04-27 21:15:42
15 UTC 2020-04-28 00:40:32
16 UTC 2020-04-28 00:47:56
17 UTC 2020-04-28 00:54:56
The main episode (#2) lasted about 12 s and released a total number of 12200 counts in the SuperAGILE RMs (over a background rate of ~100 Hz) and 103000 counts in the Anti-Coincidence RMs (over a background rate of ~5000 Hz). The other bursts all exhibited durations of the order of ~1 s and released a number of counts from 100 to 3000.
The AGILE ratemeters light curves can be found at: http://www.agilescienceapp.it/notices/AGILE_SGR1935+2154.png and
http://www.agilescienceapp.it/notices/AGILE_SGR1935+2154z.png.
The MiniCalorimeter detector (0.4-100 MeV) did not trigger any event related to this sequence of bursts, most likely because of the relatively soft spectrum.
Additional analysis of AGILE data is in progress.
