TITLE:   GCN CIRCULAR
NUMBER:  40753
SUBJECT: Konus-Wind detection of GRB 250615A / EP250615a
DATE:    25/06/17 11:35:08 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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-duration GRB 250615A (Swift detection: Dichiara et al., GCN 40736;
AstroSat CZTI detection: Tembhurnikar et al., GCN 40752),
coincident with the X-ray transient EP250615a (Yang et al., GCN 40743),
triggered Konus-Wind (KW) at T0=80722.429 s UT (22:25:22.429).

The burst light curve shows a multi-peaked emission pulse
which starts at ~T0-5 s and has a total duration of ~50 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/GRB250615_T80722/

As observed by Konus-Wind, the burst had
a fluence of (3.57 ± 0.50)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 5.248 s,
of (5.32 ± 0.53)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+49.408 s)
is best fit in the 20 keV - 15 MeV range by a GRB (Band) function
with the following model parameters:
the low-energy photon index alpha = -0.96 (-0.09,+0.11),
the high energy photon index beta = -2.41 (-1.15,+0.35),
the peak energy Ep = 908 (-187,+218) keV,
chi2 = 84/97 dof.

The spectrum near the peak count rate(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range by a GRB (Band) function
with the following model parameters:
the low-energy photon index alpha = -0.92 (-0.09,+0.09),
the high energy photon index beta = -2.62 (-7.38,+0.41),
the peak energy Ep = 1290 (-234,+320) keV,
chi2 = 89/93 dof.

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.