GRB 120107A
GCN Circular 12822
Subject
GBM trigger 347620337 (GRB 120107A?) : High-energy photon emission in Fermi/LAT data
Date
2012-01-09T22:43:53Z (13 years ago)
From
Weikang Zheng at U.of Michigan <zwk@umich.edu>
Weikang Zheng and Carl Akerlof, report on behalf of the ROTSE
collaboration:
High-energy photon emission in Fermi/LAT data was found to be correlated
with GBM trigger 347620337 (probably GRB 120107A). Our LAT data
processing pipeline which uses the matched filter technique (Akerlof et
al, 2010, ApJ, 725, L15; 2011 ApJ, 726, 22; Zheng et al. 2012, ApJ
745,72), detected the high-energy photon emission from 09:12:15 UT on
Jan. 7, 2012 (MET = 347620337) as a follow-up of a routine search in GBM
trigger catalogs. The GBM trigger location (Ra = 223.1, Dec = -77.96)
was about 56 degree from the LAT boresight, and the zenith angle was
about 106 degrees. ~7 photons above 100 MeV were detected within 50 s
after the burst, with the highest energy of ~1.78 GeV at 1.18s after the
burst (note that class 1 photons are not included in the pipeline
analysis since it is not automatically available from LAT data server at
the moment). The new GRB location estimated by the matched filter
technique is Ra = 246.40, Dec = -69.93 with uncertainty ~0.5 degree,
this is ~10 degrees away from the GBM trigger location.
A likelihood analysis gives a TS value of 58.9 (duration of 50 s), and
the GRB location Ra = 246.31, Dec = -69.93, which is also consistent
with the location derived from the matched filter technique.
All the pipeline results can be found in the following link, including
the skymap and light curve figures:
http://www.rotse.net/LAT/GBMTriggers/347620337/347620337_res.html
GCN Circular 12823
Subject
IPN Triangulation of GRB 120107A
Date
2012-01-10T16:47:43Z (13 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
K. Hurley, and J. Goldsten, on behalf of the MESSENGER NS 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,
V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi
GBM team, and
K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro,
Y. Terada, T. Murakami, and K. Makishima on behalf of the Suzaku WAM
team, report:
The long GRB 120107A, seen by Fermi/GBM (trigger 347620337) and
localized by Fermi/LAT (Zheng and Akerlof, GCN 12822), was also detected
by Konus-Wind, Suzaku (WAM), and MESSENGER (GRNS) at about 33135 s UT
(09:12:15).
Triangulation gives a MESSENGER-GBM annulus centered at RA(2000)=268.419
deg (17h 53m 40s) Dec(2000)=-23.372 deg (-23d 22' 18"), whose radius is
48.611 � 0.094 deg (3 sigma); and a Konus-GBM annulus centered at
RA(2000)=262.874 deg (17h 31m 30s) Dec(2000)=-24.735 deg (-24d 44'
05"), whose radius is 47.383 � 1.667 deg (3 sigma). These annuli
intersect at grazing incidence to form a very long box (an annulus
segment). The Fermi/LAT position (Zheng and Akerlof, GCN 12822) is
entirely contained within the Konus-GBM annulus, and intersected by the
MESSENGER-GBM annulus resulting in the IPN/LAT error box area of ~600
sq. arcmin.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB120107_T33132/IPN/
showing the LAT best-fit position (red star), and the IPN annuli (solid
lines with centers dot-dashed).
Follow-up observations of the LAT error box by the Swift satellite are
in progress.
GCN Circular 12824
Subject
Konus-Wind observation of GRB 120107A
Date
2012-01-10T16:51:34Z (13 years ago)
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 GRB 120107A (GBM trigger 347620337;
Fermi/LAT detection: Zheng and Akerlof, GCN 12822;
IPN triangulation: Hurley et al., GCN 12823)
triggered Konus-Wind at T0=33132.445s UT (09:12:12.445)
The light curve shows multiple partly overlapped pulses.
A total duration of the burst is ~25 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB120107_T33132/
As observed by Konus-Wind the burst
had a fluence of 5.5(-1.0,+1.5)x10-6 erg/cm2,
and a 64-ms peak flux, measured from T0-0.128 s,
of 1.2(-0.2,+0.3)x10-6 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).
The time-integrated spectrum of the burst
(measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model, for which
alpha = -1.38 (-0.26, +0.33),
and Ep = 196(-54, +160) keV,
chi2 = 82.5/58 dof.
The spectrum at the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model, for which
alpha = -0.98 (-0.34, +0.41),
and Ep = 178(-37, +72) keV,
chi2 = 60.0/58 dof.
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
GCN Circular 12826
Subject
GRB 120107A: Fermi GBM observation
Date
2012-01-10T18:00:19Z (13 years ago)
From
Sheila McBreen at MPE <smcbreen@mpe.mpg.de>
S. McBreen (UCD/MPE)
reports on behalf of the Fermi GBM Team:
"At 09:12:15.41 UT on 07 January 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120107A (trigger 347620337/120107384)
which was also detected by the Fermi/LAT
(Zheng and Akerlof 2012, GCN 12822).
The GBM light curve consists of about six pulses
with a duration (T90) of about 23 s (50-300 keV).
The time-averaged spectrum from T0 s to T0+23 s is
well fit by a Band function with
Epeak = 188.90 (+24.90/-22.20) keV,
alpha = -0.91 (+0.08/-0.07), and beta = -2.11 (+0.12/-0.19).
The event fluence (10-1000 keV) in this time interval is
(6.81 +/- 0.06)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.003 s in the 10-1000 keV band
is 5.55 +/- 0.24 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 12828
Subject
GRB 120107A: Suzaku WAM observation of the prompt emission
Date
2012-01-12T04:23:47Z (13 years ago)
From
Kazutaka Yamaoka at Aoyama Gakuin U <yamaoka@phys.aoyama.ac.jp>
W. Iwakiri, M. Tashiro, Y. Terada, T. Yasuda, K. Takahara, M. Asahina,
S. Kobayashi, A. Sakamoto (Saitama U.) Y. Hanabata, T. Uehara, T. Kawano,
K. Takaki, M. Mizuno, M. Ohno, Y. Fukazawa (Hiroshima U.),
S. Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), M. Kokubun,
T. Takahashi (ISAS/JAXA), Y. E. Nakagawa (Waseda U.), N. Ohmori, M. Akiyama,
M. Yamauchi (Univ. of Miyazaki), C-J. Chuang, Y. Urata, P. Tsai (NCU),
K. Nakazawa, K. Makishima (Univ. of Tokyo),
on behalf of the Suzaku WAM team, report:
The long GRB 120107A (Fermi-GBM trigger 347620337; Fermi-LAT detection:
Zheng & Akerlof, GCN 12822; IPN triangulation: Hurley et al., GCN 12823)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy
range of 50 keV - 5 MeV at 09:12:15.352 UT (=T0).
The observed light curve shows a multi-peaked structure starting at T0-2 s
and ending at T0+24 s with a duration (T90) of about 22 seconds. The fluence
in 100 - 1000 keV was 3.98 (-0.31, +0.28) x 10^-6 erg/cm^2. The 1-s peak flux
measured from T0 s was 1.94 (-0.37, +0.22) photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-2 s to T0+24 s
is well fitted by a single power-law with a photon index of 2.43 (-0.23, +0.28)
(chi^2/d.o.f = 20.5/25).
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
The light curves for this burst are now available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html