{
  "bibcode": "2022GCN.32152....1L",
  "body": "A. Lysenko, D. Frederiks, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov,\nand T. Cline on behalf of the Konus-Wind team, report:\n\nThe long-duration GRB 220527A\n(AGILE detection: Ursi et al., GCN Circ. 32129;\nFermi-LAT detection: Bissaldi et al., GCN Circ. 32131;\nFermi-GBM detection: The Fermi GBM team, GCN Circ. 32130;\nMangan et al., GCN Circ. 32133;\nCALET detection: Yamaoka et al., GCN Circ. 32139;\nAstroSat CZTI detection: Gopalakrishnan et al., GCN Circ. 32140)\ntriggered Konus-Wind at T0=33441.517 s UT (09:17:21.517).\n\nThe burst light curve shows a multipeaked structure\nwhich starts at ~T0-4.1 s and has a total duration of ~21.3 s.\nThe emission is seen up to ~16 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB220527_T33441/\n\nAs observed by Konus-Wind, the burst\nhad a fluence of 5.98(-0.31,+0.32)x10^-5 erg/cm2,\nand a 64-ms peak flux, measured from T0+5.152s,\nof 1.73(-0.21,+0.22)x10^-5 erg/cm2/s\n(both in the 20 keV - 10 MeV energy range).\n\nThe time-averaged spectrum of the burst\n(measured from T0 to T0+13.568 s)\nis best fit in the 20 keV - 16 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.80(-0.12,+0.13),\nthe high energy photon index beta = -2.55(-0.13,+0.10),\nthe peak energy Ep = 154(-10,+10) keV\n(chi2 = 115/98 dof).\n\nThe spectrum near the maximum count rate\n(measured from T0+3.584 to T0+5.376 s)\nis best fit in the 20 keV - 16 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.49(-0.18,+0.21),\nthe high energy photon index beta = -3.24(-0.53,+0.31),\nthe peak energy Ep = 146(-9,+9) keV\n(chi2 = 72/64 dof).\n\nFor both spectra, we note a prominent count excess over the model\nat energies above ~5 MeV. The excess can be modeled by\nan additional power-law component with a photon index of <~2.\n\nAssuming the redshift z=0.857 (Xu et al., GCN Circ. 32141)\nand a standard cosmology model with H_0 = 67.7 km/s/Mpc,\nOmega_M = 0.310, and Omega_Lambda = 0.689 (Planck Collab 2018, Paper VI),\nwe estimate the following rest-frame parameters:\nthe isotropic energy release E_iso is 1.22(-0.06,+0.07)x10^53 erg,\nthe peak luminosity L_iso is 6.53(-0.81,+0.84)x10^52 erg/s,\nand the rest-frame peak energy of the time-integrated spectrum,\nEp,i,z is 286(-18,+19) keV\n\nWith the obtained estimates, GRB 220527A lies inside 68% prediction bands\nfor both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW \nGRBs\nwith known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),\nsee http://www.ioffe.ru/LEA/GRBs/GRB220527_T33441/GRB220527A_rest_frame.pdf\n\nAll the quoted errors are at the 90% confidence level.\nAll the quoted values are preliminary.",
  "circularId": 32152,
  "createdOn": 1653929949000,
  "email": "alexandra.lysenko@mail.ioffe.ru",
  "subject": "Konus-Wind observation of GRB 220527A",
  "submitter": "Alexandra Lysenko at Ioffe Institute  <alexandra.lysenko@mail.ioffe.ru>",
  "eventId": "GRB 220527A"
}