- GCN Circular #13785
Arne Rau (MPE) reports on behalf of the Fermi GBM Team:
"At 07:24:41.98 UT on 19 September 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120919A (trigger 369732284 / 120919309).
The on-ground calculated location, using the GBM trigger
data, is RA = 213.4, DEC = -46.3 (J2000 degrees,
equivalent to 14 h 14 m, -46 d 18 '), with an uncertainty
of 1.1 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 63 degrees.
Moreover, this burst was bright enough to result in a Fermi spacecraft
autonomous re-point request (ARR) maneuver.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve shows a single bright pulse
with a duration (T90) of about 22.5 s (50-300 keV).
The time-averaged spectrum from T0+0.003 s to T0+10.496 s is
best fit by a Band function with Epeak = 162 +/- 8 keV,
alpha = -0.76 +/- 0.04, and beta = -2.15 +/- 0.06
The event fluence (10-1000 keV) in this time interval is
(1.60 +/- 0.03)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+2.62 s in the 10-1000 keV band
is 25.3 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #13786
K. Hurley on behalf of the Mars Odyssey and MESSENGER GRB teams,
J. Goldsten, on behalf of the MESSENGER GRNS GRB team,
I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,
S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on
behalf of the GRS-Odyssey 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
G. Di Cocco, F. Fuschino, M. Galli, C. Labanti, and M. Marisaldi, on
behalf of the AGILE MCAL team, report:
The long-duration GRB 120919A (Fermi/GBM detection: Rau, GCN Circ.
13785) was observed by Konus-Wind, MESSENGER (GRNS), Mars Odyssey
(HEND), INTEGRAL (SPI-ACS), and AGILE (MCAL) at about 26682 s UT (07:24:42).
We have triangulated the burst to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
214.768 (14h 19m 04s) -45.564 (-45d 33' 52")
Corners:
215.108 (14h 20m 26s) -45.474 (-45d 28' 26")
214.693 (14h 18m 46s) -45.722 (-45d 43' 19")
214.428 (14h 17m 43s) -45.653 (-45d 39' 09")
214.843 (14h 19m 22s) -45.407 (-45d 24' 24")
---------------------------------------------
The error box area is 236 sq. arcmin, and its maximum
dimension is 31 arcmin (the minimum one is 12 arcmin).
This box can be improved.
The center of the GBM ground position given in
GCN Circ. 13785 is 1.2 deg from the center of this box.
- GCN Circular #13787
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-duration GRB 120919A
(Fermi-GBM detection: Rau, GCN 13785;
IPN detection and localization: Hurley et al., GCN 13786)
triggered Konus-Wind at T0=26678.597s UT (07:24:38.597)
The light curve shows a single pulse with a duration of ~8 s
followed by a weaker and softer emission till ~T0+30 s.
The emission in the main bursting episode is seen up to 7 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB120919_T26678/
As observed by Konus-Wind, the burst
had a fluence of 1.4(-0.1,+0.1)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+2.432s,
of 4.1(-0.5,+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+8.448 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model, for which
alpha = -1.05 (-0.1, +0.1),
and Ep = 225(-19, +23) keV,
chi2 = 100.3/84 dof.
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
- GCN Circular #13790
A.P. Beardmore (U. Leicester) and S.R. Oates (MSSL-UCL) report on
behalf of the Swift-XRT team:
We have analysed 4.7 ks of XRT data for the GBM and IPN-detected burst
GRB 120919A (Rau et al. GCN Circ. 13785, Hurley et al. GCN Circ.
13786), from 133.7 ks to 157.6 ks after the IPN trigger. The data are
entirely in Photon Counting (PC) mode. Two uncatalogued X-ray sources
are detected within the IPN error box with the following refined XRT
positions :
Source 1 :
RA, Dec = 214.83981, -45.56220 which is equivalent to:
RA (J2000): 14h 19m 21.56s
Dec(J2000): -45d 33m 43.9s
with an uncertainty of 3.1 arcsec (radius, 90% confidence). This
position is 181 arcsec from the centre of the IPN error box. The
source is detected with a 0.3-10 keV count rate of 0.0067 +/- 0.0014
count/s, which corresponds to an observed flux of 2.7e-13 erg cm^-2
s^-1 for a typical GRB-like spectrum.
Source 2 :
RA, Dec = 214.79040, -45.56518 which is equivalent to:
RA (J2000): 14h 19m 09.70s
Dec(J2000): -45d 33m 54.66s
with an uncertainty of 5.5 arcsec (radius, 90% confidence). This
position is 57 arcsec from centre of the IPN error box. The source is
detected with a 0.3-10 keV count rate of 0.0037 +/- 0.0011 count/s,
which corrsponds to an observed flux of 1.5e-13 erg cm^-2 s^-1 for a
typical GRB-like spectrum.
We cannot determine whether either of the sources are fading at the
present time.
This circular is an official product of the Swift-XRT team.
- GCN Circular #13791
S.R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120919A
134 ks after the IPN trigger (Hurley et al. GCN Circ. 13786)
No optical afterglow is found within the IPN error box nor
at the location of the two uncatalogued XRT sources (Beardmore et al. GCN Circ. 13790).
We note the presence of a catalogued USNO-B1 source within 4.5" of XRT source 1,
with a m2 magnitude 20.52 +\- 0.17.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
m2 133695 157598 4891 >21.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.10 in the direction of the burst
(Schlegel et al. 1998).
- GCN Circular #13821
A.P. Beardmore (U. Leicester) and S.R. Oates (MSSL-UCL) report on
behalf of the Swift-XRT team:
Further XRT follow-up observations covering the field of the GBM and
IPN-detected burst GRB 120919A (Rau et al. GCN Circ. 13785, Hurley et
al. GCN Circ. 13786) have been performed. The data total 15 ks in
Photon Counting (PC) mode, collected in three observations from 134 ks
to 573 ks after the trigger. The two X-ray sources identified within
the IPN error box after the inital XRT observation (Beardmore and
Oates, GCN C. 13790) show no evidence for fading. Likewise, none of
the additional sources seen in the XRT field, but outside the IPN
error box, show evidence for fading, implying we have not detected any
X-ray counterpart to this GRB. The 3 sigma detection limit is
approximately 2.5e-3 count/s (per 5ks observation), which corresponds
to a 0.3-10 keV flux limit of 1.0e-13 erg cm^-2 s^-1 (for a typical
GRB spectrum).
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