[vsnet-grb-info 20624] Konus-Wind observation of GRB 180510A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22722
SUBJECT: Konus-Wind observation of GRB 180510A
DATE:    18/05/14 11:16:13 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova at mail.ioffe.ru>

A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 180510A
(Swift detection of a burst: Gropp et al., GCN 22695;
Ukwatta et al., GCN 22704)
triggered Konus-Wind at T0=69881.488 s UT (19:24:41.488).

The burst light curve shows a single pulse
which starts at ~T0-6.4 s and has a total duration of ~23.5 s.
The emission is seen up to ~1 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.07(-0.14,+0.21)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0-0.064 s,
of 3.53(-1.13,+1.18)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+16.640 s)
is best fit in the 20 keV - 1.5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.14(-0.31,+0.38),
and Ep = 237(-56,+126) keV (chi2 = 93/60 dof).
Fitting by the GRB (Band) model yields
alpha = -0.62(-0.66,+1.24),
Ep = 150(-54,+131) keV,
and an upper limit on the high energy photon index:
beta < -1.90 (chi2 = 91/59 dof).

The spectrum near the peak count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model
with  alpha = -0.97(-0.30,+0.35),
and Ep = 202(-34,+54) keV (chi2 = 75/50 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.37 (chi2 = 75/49 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180510_T69881/

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.