GCN Circular 32109
Subject
Konus-Wind detection of GRB 220522B
Date
2022-05-24T20:26:44Z (3 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long-duration GRB 220522B
(IPN triangulation: Kozyrev at al., GCN Circ. 32108)
triggered Konus-Wind at T0=1058.258 s UT (00:17:38.258).
The burst light curve shows a multipeaked structure
which starts at ~T0-4.4 s and has a total duration of ~106.3 s.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220522_T01058/
As observed by Konus-Wind, the burst
had a fluence of 5.49(-1.66,+1.13)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+9.344 s,
of 5.76(-2.35,+2.67)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+41.216 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.47(-0.53,+0.56),
the high energy photon index beta = -1.94(-0.86,+0.15),
the peak energy Ep = 230(-60,+197) keV
(chi2 = 85/67 dof).
The spectrum near the maximum count rate
(measured from T0+8.448 to T0+16.640 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.37(-0.48,+0.94),
the high energy photon index beta = -2.18(-0.90,+0.28),
the peak energy Ep = 224(-72,+108) keV
(chi2 = 73/66 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.