GRB 130610B

K. Hurley and J. Goldsten, on behalf of MESSENGER GRNS GRB team,

S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team, and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:

The long-duration GRB 130610B has been observed by Konus-Wind, INTEGRAL 
(SPI-ACS), and MESSENGER (GRNS), so far, at about 76880 s UT (21:21:20).

We have triangulated it to a preliminary, 3 sigma error box whose 
coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   176.359 (11h 45m 26s) -32.187 (-32d 11' 12")
  Corners:
   176.728 (11h 46m 55s) -31.962 (-31d 57' 43")
   176.012 (11h 44m 03s) -32.983 (-32d 58' 58")
   175.989 (11h 43m 57s) -32.409 (-32d 24' 33")
   176.709 (11h 46m 50s) -31.377 (-31d 22' 36")
  ---------------------------------------------
The error box area is 0.37 sq. deg, and its maximum dimension is
1.71 deg (the minimum one is 0.31 deg).

This box may be improved.

A triangulation map is posted at 
http://www.ioffe.ru/LEA/GRBs/GRB130610_T76879/IPN/

The time history and spectrum will be given in a forthcoming GCN Circular.

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline, on behalf
of the Konus-Wind team, report:

The long-duration GRB 130610B
(IPN triangulation: Hurley at al., GCN 14868
Loading...
 
 )
triggered Konus-Wind at T0=76879.093 s UT (21:21:19.093).

The light curve  from ~T0-0.5 s to ~T0+16s shows multiple pulses
with decaying spectral hardness.
The pulses form a quasi-periodic structure with the period of ~1s
during first ~5 seconds of the burst, which is followed, after T0+7s,
by the three pulses separated by ~2.7s.

A weak count rate excess in the soft energy channel (20-80 keV)
is observed from ~T0-170 s to ~T0-100 s in the instrument
background mode; however, its attribution to GRB 130610B
is not yet confirmed.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130610_T76879/

As observed by Konus-Wind, the burst
had a fluence of (8.5 � 0.4)x10-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.256s,
of (6.0 � 0.5)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -1.7 � 0.1,
the peak energy Ep = 62 � 9 keV,
chi2 = 99/98 dof.

The 3-channel spectrum at the maximum count rate
(measured from T0+0.256 to T0+0.384 s)
can be modeled, in the 20 keV - 1.35 MeV range,
by the cutoff power law with the following model parameters:
the photon index alpha = -0.52 � 0.08,
and the peak energy Ep = 444 � 30 keV.

All the quoted results are preliminary.