Gamma-ray Burst 220524A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #32115
  A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars-Odyssey team,
  A. Ridnaia, D. Frederiks, D. Svinkin, A. Lysenko, and T. Cline on behalf of the Konus-Wind team,
  E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
  S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT 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 long-duration GRB 220524A has been detected by Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), and Mars-Odyssey (HEND), so far, at about 35587 s UT (09:53:07). 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:
     20.862 (01h 23m 27s) +46.592 (+46d 35' 30")
   Corners:
     21.916 (01h 27m 40s) +46.226 (+46d 13' 34")
     19.808 (01h 19m 14s) +47.018 (+47d 01' 03")
     19.794 (01h 19m 10s) +46.938 (+46d 56' 16")
     21.899 (01h 27m 36s) +46.146 (+46d 08' 45")
   ---------------------------------------------
  

  The error box area is 447 sq. arcmin, and its maximum dimension is 1.68 deg (the minimum one is 4.6 arcmin). The Sun distance was 41 deg.
  This box may be improved.
  A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB220524_T35587/IPN/
  The time history and spectrum will be given in forthcoming GCN Circulars.
• GCN Circular #32121
  D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
  The long GRB 220524A (IPN triangulation: Kozyrev et al., GCN 32115) triggered Konus-Wind (KW) at T0=35587.191 s UT (09:53:07.191).
  The burst light curve shows a multi-peaked structure, which starts at ~T0-0.5 s and has a total duration of ~2.5 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/GRB220524_T35587/
  As observed by Konus-Wind, the burst had a fluence of (4.0 ± 0.6)x10^-6 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 2.048 s, of (6.1 ± 1.0)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
  A time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is well fit in the 20 keV - 15 MeV range by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.22(-0.23,+0.27) and Ep = 186(-38,+63) keV (chi2 = 93/98 dof). Fitting this spectrum by a Band function yields the same values of alpha and Ep, and an upper limit on the high energy photon index beta of -2.2 (chi2 = 92/97 dof).
  All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.