GRB 211206A
GCN Circular 31181
Subject
GRB 211206A: Not observable by Fermi-GBM
Date
2021-12-07T18:45:02Z (4 years ago)
From
Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>
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.
GCN Circular 31180
Subject
GRB 211206A: AstroSat CZTI detection
Date
2021-12-07T10:12:35Z (4 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
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
GCN Circular 31176
Subject
GRB 211206A: Swift/BAT-GUANO detection outside the coded FOV
Date
2021-12-07T02:42:06Z (4 years ago)
From
Aaron Tohuvavohu at U Toronto <aaron.tohu@gmail.com>
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/
GCN Circular 31175
Subject
GRB 211206A: AGILE/MCAL detection of a burst
Date
2021-12-06T22:32:53Z (4 years ago)
From
Alessandro Ursi at INAF/IAPS <alessandro.ursi@gmail.com>
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.