////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  12018
SUBJECT: IPN localization of bright GRB 110518A
DATE:    11/05/19 23:20:59 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val@mail.ioffe.ru>

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

K. Hurley on behalf of the Mars Odyssey and MESSENGER GRB teams,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

J. Goldsten on behalf of the MESSENGER GRNS GRB team,

A. von Kienlin, X. Zhang, and A. Rau, on behalf of the
INTEGRAL SPI-ACS GRB team,

D. Smith, J. McTiernan, R. Schwartz, and W. Hajdas, on behalf
of the RHESSI GRB team,

and

J. Cummings, D. Palmer, S. Barthelmy, N. Gehrels, and H. Krimm, on
behalf of the Swift-BAT team, report:

Konus-Wind, Swift (BAT), INTEGRAL SPI-ACS, RHESSI, Mars Odyssey (HEND), 
and MESSENGER (GRNS) observed the long bright GRB 110518A at about 
20:38:14 UT. The burst was outside the coded  field of view of the BAT.

We have triangulated it to a 3 sigma error box whose coordinates are:
-----------------------------------------------
    RA(2000), deg              Dec(2000), deg
-----------------------------------------------
Center:
   67.180 (04h 28m 43s)   -34.195 (-34d 11' 43")
Corners:
   67.910 (04h 31m 38s)   -33.755 (-33d 45' 18")
   66.826 (04h 27m 18s)   -34.525 (-34d 31' 28")
   66.438 (04h 25m 45s)   -34.626 (-34d 37' 35")
   67.529 (04h 30m 07s)   -33.864 (-33d 51' 51")
-----------------------------------------------
The error box area is 536 sq. arcmin.
The maximum distance between the box corners is 1.5 deg.
This error box may be improved.

Spectral information will be reported in a forthcoming GCN Circular.

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  12019
SUBJECT: Konus-Wind observation of GRB 110518A
DATE:    11/05/20 12:32:02 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long bright GRB 110518A (localized by IPN:
Golenetskii et al., GCN 12018)
triggered Konus-Wind at T0=74290.767s UT (20:38:10.767)

The burst light curve consists of two major pulses,
a total duration of the burst is ~35 s.
The emission in the first harder multi-peaked pulse
is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB110518_T74290/

As observed by Konus-Wind the burst
had a fluence of (6.5 ± 0.8)x10-5 erg/cm2,
and a 16-ms peak flux, measured from T0+0.400 s,
of (4.7 ± 0.5)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+35.072 s) is best fitted
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -1.29 (-0.07, +0.08),
the high energy photon index beta = -2.30 (-0.35, +0.15),
the peak energy Ep = 229(-35, +43) keV,
chi2 = 102.6/84 dof.

The spectrum at the maximum count rate
(measured from T0+0.256 s to T0+0.512 s) is best fitted
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.46 (-0.16, +0.18),
the high energy photon index beta = -2.6 (-0.7, +0.3),
the peak energy Ep = 535(-88, +123) keV,
chi2 = 50.4/48 dof.

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