Gamma-ray Burst 200327A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #27458
The Fermi GBM team reports the detection of a likely SHORT GRB
At 20:56:48 UT on 27 Mar 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200327A (trigger 607035413.165342 / 200327873).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 233.4, Dec = 2.4 (J2000 degrees, equivalent to J2000 15h 33m, 2d 23'), with a statistical uncertainty of 17.5 degrees.
The angle from the Fermi LAT boresight is 109.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200327873/quicklook/glg_skymap_all_bn200327873.png
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200327873/quicklook/glg_healpix_all_bn200327873.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200327873/quicklook/glg_lc_medres34_bn200327873.gif
GCN Circular #27461
A. Ursi (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, (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 short burst GRB 200327A reported by Fermi/GBM (GCN #27458), that also triggered the automatic AGILE Mini-CALorimeter (MCAL) GRB alert Notice (ID 512427408), published at: https://gcn.gsfc.nasa.gov/agile_mcal.html.
The event was detected by MCAL at T0 = 2020-03-27 20:56:48.25 +/- 0.01 s (UTC), lasting ~0.13 s and releasing a total number of ~150 counts in the detector, above a background rate of ~530 Hz. The MCAL light curve can be found at: http://www.agilescienceapp.it/notices/GRB_067116_512427408.252268.png. The time-integrated spectrum of the burst in 0.13 s can be fitted in the energy range 0.4-10 MeV with a single power-law with ph.ind. = 2.56 -0.43/+0.54, resulting in a reduced chi-squared of 1.19 (8 d.o.f.). The burst fluence in the same energy range and time interval is 6.34e-07 erg/cm^2 (90% confidence level).
At the T0, the event localization according to Fermi/GBM, RA = 233.4, Dec = 2.4 (J2000) was outside the AGILE Gamma-Ray Imaging Detector (GRID) Field-of-View.
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.
GCN Circular #27463
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team,
K. Hurley, on behalf of the IPN,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
and
S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, report:
The short-duration GRB 200327A (Fermi-GBM detection: The Fermi GBM Team, GCN Circ. 27458; AGILE-MCAL detection: Ursi, et al., GCN Circ. 27461) was detected by Fermi (GBM trigger 607035413), Konus-Wind, INTEGRAL (SPI-ACS), AGILE (MCAL), and Swift (BAT) at about 75408 s UT (20:56:48). 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:
   236.574 (15h 46m 18s)  -4.217 ( -4d 13' 02")
  Corners:
   236.885 (15h 47m 32s)  -2.457 ( -2d 27' 24")
   236.477 (15h 45m 54s)  -5.963 ( -5d 57' 48")
   236.244 (15h 44m 59s)  -5.977 ( -5d 58' 36")
   236.654 (15h 46m 37s)  -2.472 ( -2d 28' 18")
  ---------------------------------------------
```
The error box area is 2897 sq. arcmin, and its maximum dimension is 3.6 deg (the minimum one is 13.7 arcmin). The Sun distance was 130 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of, the Fermi-GBM final position (GCN Circ. 27458).
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB200327_T75409/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #27466
P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
"At 20:56:48.17 UT on 27 March 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 200327A (trigger 607035413 / 200327873) which was also detected by AGILE-MCAL (Ursi et al., GCN 27461) and localized by IPN (Svinkin et al., GCN 27463). The GBM on-ground location is consistent with the IPN position.
The angle from the Fermi LAT boresight at the GBM trigger time is 104 degrees.
The GBM light curve consists of two pulses with a duration (T90) of about 0.64 s (50-300 keV). The time-averaged spectrum from T0-64 ms to T0+192 ms is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.60 +/- 0.09 and the cutoff energy, parameterized as Epeak, is 1100 +/- 180 keV.
The event fluence (10-1000 keV) in this time interval is (1.53 +/- 0.06)E-6 erg/cm^2. The 64 ms peak photon flux measured starting from T0+64 ms in the 10-1000 keV band is 19.2 +/- 1.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular #27525
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report:
The short-duration GRB 200327A (Fermi-GBM detection: The Fermi GBM Team, GCN Circ. 27458; Veres and Meegan, GCN Circ. 27466; AGILE-MCAL detection: Ursi, et al., GCN Circ. 27461; IPN triangulation: Svinkin et al., GCN Circ. 27463) triggered Konus-Wind at T0=75409.744 s UT (20:56:49.744).
The burst light curve shows a double-peaked structure which starts at ~T0-0.1 s and has a total duration of ~0.2 s. The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB200327_T75409/
As observed by Konus-Wind, the burst had a fluence of 2.32(-0.67,+0.82)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-0.016 s, of 2.45(-1.16,+1.37)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+0.064 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.56(-0.36,+0.52) and Ep = 1323(-545,+961) keV (chi2 = 11/14 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2 (chi2 = 11/13 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.

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Jochen Greiner, last update: 10-Apr-2020 [Disclaimer]