GCN Circular 17900
Subject
Konus-Wind observation of GRB 150530A
Date
2015-06-03T17:40:38Z (9 years ago)
From
Anastasia Tsvetkova at Ioffe Institute <tsvetkova@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 150530A (Swift-BAT trigger #642018:
Starling et al., GCN 17888; Markwardt et al., GCN 17890;
Fermi GBM detection: Yu, Younes and Meegan, GCN 17891)
triggered Konus-Wind at T0=42136.529 s UT (11:42:16.529).
The burst light curve shows a single pulse lasting from ~T0-4 s to ~T0+6 s.
The emission is seen up to ~1.2 MeV.
As observed by Konus-Wind, the burst
had a fluence of 2.54(-0.26,+0.28)x10^-6 erg/cm2,
and a 64-ms peak energy flux, measured from T0+0.082 s,
of 1.06(-0.43,+0.43)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1.2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.63(-0.38,+0.46),
and Ep = 114(-17,+23) keV (chi2 = 59/58 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -3.07 (chi2 = 59/57 dof).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150530_T42136/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.