- GCN Circular #13620
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 IPN,
V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi
GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and
S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on
behalf of the Swift-BAT team, report:
The short hard GRB 120811B has been observed by Fermi (GBM: trigger
366337233), Konus-Wind, INTEGRAL (SPI-ACS), and Swift (BAT), so far, at
about 1230 s UT (00:20:30).
We have triangulated the burst to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
43.719 (02h 54m 53s) -30.233 (-30d 13' 58")
Corners:
43.568 (02h 54m 16s) -28.355 (-28d 21' 19")
43.930 (02h 55m 43s) -27.828 (-27d 49' 40")
43.853 (02h 55m 25s) -32.184 (-32d 11' 04")
43.457 (02h 53m 50s) -32.775 (-32d 46' 30")
---------------------------------------------
The error box area is 1.39 sq. deg, and its maximum dimension is 4.96 deg.
This box can be improved.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB120811_T01231/IPN/
The time history and spectrum will be given in a forthcoming GCN Circular.
- GCN Circular #13621
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 short-duration hard GRB 120811B
(IPN localization: Golenetskii at al., GCN 13620)
triggered Konus-Wind at T0=01231.575s UT (00:20:31.575)
The light curve shows a double pulse,
a total duration of the burst is ~0.33 s.
The emission is seen up to ~6 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB120811_T01231/
As observed by Konus-Wind the burst
had a fluence of 4.6(-0.9,+1.0)x10-6 erg/cm2,
and a 16-ms peak flux, measured from T0,
of 2.8(-0.6,+0.7)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 7 MeV range
by a power law with exponential cutoff model, for which
alpha = -0.14 (-0.28, +0.35),
and Ep = 1130(-230, +310) keV,
chi2 = 13.6/24 dof.
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
- GCN Circular #13627
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, and J. Goldsten, on behalf of the MESSENGER GRNS GRB team,
V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi
GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and
S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on
behalf of the Swift-BAT team, report:
This burst (GCN 13620) was also observed by MESSENGER (GRNS). We have
triangulated it to an improved, but still preliminary 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
43.658 (02h 54m 38s) -31.675 (-31d 40' 29")
Corners:
43.770 (02h 55m 05s) -32.366 (-32d 21' 59")
43.820 (02h 55m 17s) -31.614 (-31d 36' 51")
43.545 (02h 54m 11s) -30.978 (-30d 58' 42")
43.495 (02h 53m 59s) -31.735 (-31d 44' 06")
---------------------------------------------
The error box area is 734 sq. arcmin, and its maximum
dimension is 84 arcmin.
This error box is fully contained within the previous IPN error box (GCN
13620).
This box can be further improved.
An updated triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB120811_T01231/IPN/
- GCN Circular #13644
Shaolin Xiong (UAH) and Chip Meegan (USRA)
report on behalf of the Fermi GBM Team:
"At 00:20:31.288 UT on 11 August 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120811B (trigger 366337233 / 120811014),
which was also located by the IPN (S. Golenetskii et al. 2012, GCN 13627).
The GBM on-ground location is consistent with the IPN position.
The angle from the Fermi LAT boresight is 85 degrees.
The GBM light curve consists of two pulses
with a duration (T90) of about 0.448 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.384 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.29 +/- 0.09 and
the cutoff energy, parameterized as Epeak, is 1294 +/- 145 keV.
The event fluence (10-1000 keV) in this time interval is
(2.45 +/- 0.10)E-6 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.064 s in the 10-1000 keV band
is 21.0 +/- 1.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
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