TITLE:   GCN CIRCULAR
NUMBER:  44617
SUBJECT: Konus-Wind detection of GRB 260512A
DATE:    26/05/15 10:45:03 GMT
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 260512A
(Fermi-GBM detection: The Fermi GBM team, GCN 44587;
NuSTAR-ACS detection: Waratkar et al., GCN 44591;
AstroSat-CZTI detection: Tembhurnikar et al., GCN 44608;
IPN triangulation: Kozyrev et al., GCN 44611)
triggered Konus-Wind at T0=61005.883 s UT (16:56:45.883).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.7 s and has a total duration of ~23 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/GRB260512_T61005/

As observed by Konus-Wind, the burst
had the total fluence of 2.45(-0.24,+0.20)x10^-5 erg/cm2,
and the 64-ms peak flux, measured from T0+4.464 s,
of 6.32(-0.82,+0.83)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+24.832 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.99(-0.09,+0.09),
the high energy photon index beta = -2.60(-0.46,+0.17),
the peak energy Ep = 202(-16,+22) keV
(chi2 = 117/98 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.82(-0.08,+0.08),
the high energy photon index beta = -2.53(-0.13,+0.10),
the peak energy Ep = 193(-11,+13) keV
(chi2 = 93/79 dof).

All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.