Gamma-ray Burst 220308A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #31715
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team,
E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
and
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, report:
The very bright, long-duration GRB 220308A has been detected by Konus-Wind, INTEGRAL (SPI-ACS), Fermi (GBM), Swift (BAT), and AGILE (MCAL), so far, at about 20588 s UT (05:43:08). The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   356.500 (23h 46m 00s) +23.844 (+23d 50' 40")
  Corners:
   358.094 (23h 52m 23s) +22.701 (+22d 42' 02")
   355.336 (23h 41m 21s) +25.088 (+25d 05' 19")
   354.810 (23h 39m 15s) +24.953 (+24d 57' 11")
   357.591 (23h 50m 22s) +22.579 (+22d 34' 45")
  ---------------------------------------------
```
The error box area is 1.44 sq. deg, and its maximum dimension is 3.75 deg (the minimum one is 25 arcmin). The Sun distance was 30 deg.
This box may be improved.
A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB220308_T20585/IPN/
The time history and spectrum will be given in forthcoming GCN Circulars.
GCN Circular #31716
Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri Raman (PSU), Jamie A. Kennea (PSU), report:
Swift/BAT did not localize GRB 220308A onboard (T0: 2022-03-08T05:43:08 UTC, INTEGRAL/SPI-ACS trig#9761, IPN GCN 31715).
The INTEGRAL 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 97 in a 8.192 s analysis time bin. The duration of this burst episode is ~10s.
NITRATES results indicate a burst coming from outside the coded FOV, with DeltaLLHOut of -240. An out of FOV origin is consistent with the IPN timing localization (GCN 31715).
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 #31719
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 05:35:27.809 UTC on 8 March 2022, the CALET Gamma-ray Burst Monitor (CGBM) triggered on a long weak GRB followed in ~460 s by the bright GRB 220308A, localized by the IPN (Svinkin et al., GCN 31715; https://gcn.gsfc.nasa.gov/other/220308A.gcn3). Both bursts were seen by all CGBM detectors. The first (trigger) burst might be a precursor of GRB 220308A.
The trigger burst light curve shows a double-peaked pulse which starts at T+1.9 sec, peaks at T+3.6 sec,and ends at T+15.0 sec. The T90 and T50 durations measured by the SGM data are 11.6 +- 1.6 sec and 7.4 +- 1.6 sec (40-1000 keV), respectively. The GRB 220308A light curve shows a multi-peaked structure which starts at T+461.6 sec, peaks at T+465.9 sec, and ends at T+481.9 sec. The T90 and T50 durations measured by the SGM data are 15.4 +- 0.4 sec and 4.0 +- 0.1 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1330752907/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.
GCN Circular #31723
D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 220308A (IPN triangulation: Svinkin et al., GCN Circ. 31715; Swift/BAT-GUANO detection: Tohuvavohu et al., GCN Circ. 31716; CALET-CGBM detection: Marrocchesi et al., GCN Circ. 31719) triggered Konus-Wind at T0=20585.134 s UT (05:43:05.134).
The burst light curve shows a multipeaked structure which starts at ~T0-0.1 s and has a total duration of ~69 s. The emission is seen up to ~15 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB220308_T20585/
As observed by Konus-Wind, the burst had a fluence of 2.87(-0.11,+0.11)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+1.296 s, of 1.06(-0.10,+0.10)x10^-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+22.016 s) is best fit in the 20 keV - 16 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.93(-0.02,+0.02), the high energy photon index beta = -3.42(-6.58,+0.47), the peak energy Ep = 1099(-55,+57) keV (chi2 = 130/97 dof).
The spectrum near the maximum count rate (measured from T0+1.024 to T0+1.536 s) is best fit in the 20 keV - 16 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.26(-0.09,+0.10), the high energy photon index beta = -3.13(-1.01,+0.41), the peak energy Ep = 1419(-150,+155) keV (chi2 = 69/66 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #31733
A. Ursi (INAF/IAPS), A. Di Piano (INAF/OAS-Bologna), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, E. Menegoni, L. Foffano, G. Piano (INAF/IAPS), F. Lucarelli (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 satellite detected the long GRB 220308A at T0 = 2022-03-08 05:43:08 (UTC), reported by INTEGRAL/SPI-ACS (trig#9761), Fermi/GBM (trigger no.668410535), CALET (GCN #31719), Konus-Wind (GCN #31723), Swift/BAT (GCN #31716), and triangulated by IPN (GCN #31715).
The burst is 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 22 s and it released a total number of 2675 counts in the SA detector (above a background rate of 140 Hz), 54840 counts in the MCAL detector (above a background rate of 1300 Hz), and 104080 counts in the AC detector (above a background rate of 3680 Hz). The AGILE ratemeter light curves can be found at https://tools.ssdc.asi.it/ImgView/Agile/GRB220308A_AGILE_RM29 .
The event also triggered a partial high time resolution MCAL data acquisition, covering the main peaks of the burst, from T1 = 2022-03-08 05:43:08.21 s +/- 0.01 (UTC) to T2 = 2022-03-08 05:43:15.06 +/- 0.01 s (UTC), and released 16490 counts in the detector, above a background rate of 640 Hz. The time-integrated spectrum of the burst in this time interval can be fitted in the energy range 0.4-10 MeV with a Band function with alpha = -0.70 (frozen), beta = -2.45 (-0.11/+0.09), and Epeak = 760 (-98/+97) keV, resulting in a reduced chi-squared of 1.32 (47 d.o.f.) and a fluence of 1.4e-04 ergs/cm^2 (90% confidence level), in the same energy range. The MCAL light curve can be found at: https://tools.ssdc.asi.it/ImgView/Agile/077313_GRB_57380300810779330 .
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. Please note that in the MCAL notice #573803008 the T0 was affected by a temporal shift of about +19.5 sec due to episodic automated ground software problems which are then corrected offline.
GCN Circular #31734
C. Fletcher (USRA), O. J. Roberts (USRA) and J. Wood (NASA/MSFC) report on behalf of the Fermi-GBM Team:
Swift/BAT-GUANO detected GRB 220308A at 05:43:08 UT (GCN 31716), which was also detected by INTEGRAL/SPI-ACS (trig#9761), IPN (GCN 31715), Konus-Wind (GCN 31723), CGBM (GCN 31719), and AGILE (GCN 31733).
The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals identified a transient most significantly on the 2.048 s consistent with GRB 220308A. The GBM targeted search location is RA=350.6, DEC = 4.7 (J2000 degrees, equivalent to 23 h 22 m, 04 d 42'), with an approximate 68% error radius of 10.6 degrees (statistical plus a core-plus-tail systematic model, with 77% of GRBs having a 2.4 deg error and the remaining fraction having a 10.9 deg error.)
The time-averaged spectrum (using a T0 of 2022-03-08T05:43:00 UT) from T0+8.000 s to T0+28.480 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.0 +/- 0.0 and the cutoff energy, parameterized as Epeak = 1371 +/- 26 keV. The event fluence (10-1000 keV) in this time interval is (1.53 +/- 0.05)E-04 erg/cm^2.
There was a Fermi-GBM onboard trigger of a gamma-ray burst (GRB 220308B, GCN 31726) approximately 460 s before GRB 220308A, however, we do not believe these two events to be related.
The spectral analysis results presented above are preliminary.
[1] Goldstein et al. 2019 arXiv:1903.12597

Back to JG's homepage

Jochen Greiner, last update: 10-Mar-2022 [Disclaimer]