//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31175 SUBJECT: GRB 211206A: AGILE/MCAL detection of a burst DATE: 21/12/06 22:32:53 GMT FROM: Alessandro Ursi at INAF/IAPS A. Ursi (INAF/IAPS), C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, L. Foffano, E. Menegoni, G. Piano (INAF/IAPS), F. Lucarelli, F. Verrecchia (SSDC, and INAF/OAR), A. Bulgarelli, V. Fioretti, F. Fuschino, N. Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F. Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team: The AGILE Mini-CALorimeter (MCAL) detected a burst at T0 = 2021-12-06 19:51:10.80 +/- 0.01 s (UTC). The event lasted about 4.5 s and released a total number of ~3374 counts in the detector (in the 0.4-100 MeV energy range), above an average background rate of 599 Hz. The MCAL light curve shows two main peaks and can be found at http://www.agilescienceapp.it/notices/075998_GRB_MCAL_565905070.805285.png The burst is also clearly visible in the AGILE scientific ratemeters of the SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about 5 s and it released a total number of 853 counts in the SA detector (above a background rate of 90 Hz), 8286 counts in the MCAL detector (above a background rate of 1260 Hz), and 18890 counts in the AC detector (above a background rate of 3600 Hz). The AGILE ratemeter light curves can be found at http://www.agilescienceapp.it/notices/GRB211206A_AGILE_RM.png The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31176 SUBJECT: GRB 211206A: Swift/BAT-GUANO detection outside the coded FOV DATE: 21/12/07 02:42:06 GMT FROM: Aaron Tohuvavohu at U Toronto James DeLaunay (UAlabama), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Jamie A. Kennea (PSU), report: Swift/BAT detected a rate increase onboard (trigger ##1088092) but did not localize GRB 211206A (T0: 2021-12-06T19:51:10 UTC, AGILE/MCAL GCN 31175, CALET trig #1322855382). The CALET notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-45,+45] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, arXiv:2111.01769), detects the burst with a sqrt(TS) of 74.6 in a 4.096 s analysis time bin. Estimated T90 in the detector is 6.6 +/- 0.2 s (15-350 keV). NITRATES results strongly prefer an origin for the burst coming from outside the coded FOV, with DeltaLLHOut of -55.5. See Section 9.1 and Figure 20 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31180 SUBJECT: GRB 211206A: AstroSat CZTI detection DATE: 21/12/07 10:12:35 GMT FROM: Gaurav Waratkar at IIT,Bombay V. Prasad (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed detection of a long GRB 211206A which was also detected by AGILE/MCAL (Ursi et al., GCN 31175) and Swift/BAT-GUANO (DeLaunay et al., GCN 31176). The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2021-12-06 19:51:12.450 UT. The measured peak count rate associated with the burst is 776 (+198, -60) cts/s above the background in the combined data of two quadrants, with a total of 1947 (+221, -223) cts. The local mean background count rate was 443 (+7, -10) cts/s. Using cumulative rates, we measure a T90 of 4.3 (+1.3, -0.6) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2021-12-06 19:51:12.088 UT. The measured peak count rate is 1509 (+86, -95) cts/s above the background in the combined Veto data of four quadrants, with a total of 5582 (+310, -365) cts. The local mean background count rate was 1466 (+4, -4) cts/s. We measure a T90 of 6.6 (+1.5, -1.6) s from the cumulative Veto light curve. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. Links: ------ [1] http://astrosat.iucaa.in/czti/?q=grb //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31181 SUBJECT: GRB 211206A: Not observable by Fermi-GBM DATE: 21/12/07 18:45:02 GMT FROM: Oliver J Roberts at USRA/NASA O.J. Roberts (USRA/NASA-MSFC) reports on behalf of the Fermi-GBM team: Fermi-GBM was passing through the South Atlantic Anomaly from 9.4 minutes prior to the trigger time of GRB 211206A (GCNs 31175,31176 and 31180), until 14.3 minutes after, over which time the GBM detectors were disabled.