Gamma-ray Burst 220320A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #31779
  R. Gopalakrishnan (IUCAA), V. Prasad (IUCAA), A. Suresh (IITB), 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 ML pipeline (Abraham et al., 2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed detection of a bright long GRB 220320A which was also detected by IPN (contributed by Konus-Wind at GCN Notices), and Fermi - GBM (Trigger - 669443999).
  The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2022-03-20 04:39:59.25 UT. The measured peak count rate associated with the burst is 2398 (+336, -71) counts/s above the background in the combined data of four quadrants, with a total of 5427 (+307, -331) counts. The local mean background count rate was 507 (+5, -9) counts/s. Using cumulative rates, we measure a T90 of 11 (+1, -1) s.
  It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a peak at 2022-03-20 04:39:59.13 UT. The measured peak count rate is 3438 (+112, -122) counts/s above the background in the combined Veto data of four quadrants, with a total of 10543 (+502, -570) counts. The local mean background count rate was 1529 (+5, -5) counts/s. We measure a T90 of 16 (+3, -3) 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 #31783
  A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the MGNS/BepiColombo and HEND/Mars Odyssey teams,
  J. Benkhoff on behalf of the BepiColombo team,
  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
  W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report:
  The bright, long-duration GRB 220320A (AstroSat-CZTI detection: Gopalakrishnan et al., GCN Circ. 31779) was detected by Fermi (GBM trigger 669443999), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), BepiColombo (MGNS), CALET (CGBM), and AstroSat (CZTI) at about 16794 s UT (04:39:54).
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

    ---------------------------------------------
     RA(2000), deg                 Dec(2000), deg
    ---------------------------------------------
    Center:
      94.150 (06h 16m 36s) -55.909 (-55d 54' 31")
    Corners:
      94.226 (06h 16m 54s) -55.949 (-55d 56' 58")
      94.048 (06h 16m 12s) -55.915 (-55d 54' 54")
      94.074 (06h 16m 18s) -55.868 (-55d 52' 04")
      94.252 (06h 17m 00s) -55.902 (-55d 54' 08")
    ---------------------------------------------
  

  The error box area is 19 sq. arcmin, and its maximum dimension is 7 arcmin (the minimum one is 3 arcmin). The Sun distance was 92 deg.
  This box may be improved.
  The IPN localization is consistent with, but reduces the area of, the Fermi GBM final position.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB220320_T16796/IPN
  The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
• GCN Circular #31802
  A. Tsvetkova,  D. Frederiks, D. Svinkin, M. Ulanov, A. Lysenko, A. Ridnaia and T. Cline on behalf of the Konus-Wind team, report:
  The long-duration, bright GRB 220320A (AstroSat CZTI detection: Gopalakrishnan et al., GCN 31779; IPN triangulation: Kozyrev et al., GCN 31783) triggered Konus-Wind at T0=16796.141 s UT (04:39:56.141).
  The burst light curve shows a multi-peaked structure which starts at ~T0-18.8 s and has a total duration of~52.8 s The emission is seen up to ~20 MeV.
  As observed by Konus-Wind, the burst had a fluence of 6.05(-0.50,+0.52)x10^-5 erg/cm2, and a 64-ms peak energy flux, measured from T0+4.048 s, of 2.50(-0.34,+0.34)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum of the burst (measured from T0 to T0+20.480 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.84(-0.09,+0.10), the high energy photon index beta = -2.27(-0.15,+0.11), the peak energy Ep = 224(-21,+24) keV, chi2 = 100/97 dof.
  The spectrum near the peak count rate (measured from T0 to T0+4.352 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.43(-0.11,+0.12), the high energy photon index beta = -2.31(-0.17,+0.13), the peak energy Ep = 311(-29,+33) keV, chi2 = 67/86 dof.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB220320_T16796/
  All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
• GCN Circular #31803
  J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), M. Ohno (Eotvos U./Hiroshima U.),  N. Werner  (Masaryk U.),  L. Meszaros (Konkoly Observatory), H. Takahashi (Hiroshima U.), B. Csak (Konkoly Observatory), M. Topinka, F. Munz, F. Hroch (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.
  The bright, long-duration GRB 220320A (AstroSat-CZTI detection: Gopalakrishnan et al., GCN Circ. 31779; localized by IPN: Kozyrev et al. GCN Circ. 31783 and detected also by Fermi/GBM trigger 669443999, CALET/CGBM trigger 1331786356, Konus-Wind, INTEGRAL/SPI-ACS at about 04:39:54 UT) was also detected by one of the two GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).
  This is the first time that a GRB was observed by the VZLUSAT-2 3U CubeSat.
  The data acquisition was performed by GRB detector unit no. 1 (the unit no. 0 was turned off). The detector was performing a several hours long background monitoring survey with 15 s temporal resolution, which is not optimal for GRB search. Much finer resolution is planned for the nominal operation. The 46 sigma detection significance was confirmed at around 04:39:55 UTC.
  The light curve obtained by VZLUSAT-2 is available here: https://vzlusat2.konkoly.hu/static/share/GRB220320A_GCN_VZLUSAT_2.pdf
  GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSats constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.