GRB 100724B
GCN Circular 10977
Subject
GRB 100724B: Fermi GBM detection
Date
2010-07-24T23:28:20Z (15 years ago)
From
Narayana Bhat at U Alabama/Huntsville/GBM <Narayana.Bhat@nasa.gov>
P. N. Bhat (UAH)
reports on behalf of the Fermi GBM Team:
"At 00:42:05.98 UT on 24 July 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100724B (trigger 301624927 / 100724029).
The on-ground calculated location, using the GBM trigger
data, is RA = 124.16, DEC = 74.42 (J2000 degrees,
equivalent to 08 h 16.6 m, 74 d 25.2 '), with an uncertainty
of 1.0 degree (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 52 degrees.
GBM triggered an automatic repoint request to the Fermi
Observatory to execute a maneuver following this trigger
and track the burst location for the next 5 hours.
However due to spacecraft constraints, the slew did not
commence until 2733 s after the trigger.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve consists of several pulses
with a duration (T90) of about 111.6 s (50-300 keV).
The time-averaged spectrum from T0-5.12 s to T0+140.29 s is
best fit by a Band function with Epeak = 467.8 +15.3/-13.1 keV,
alpha = 0.84 +/- 0.01, and beta = -1.84 +/- 0.01
(Cstat 18069 for 736 d.o.f.).
The event fluence (8-1000 keV) in this time interval is
(2.44 +/- 0.006)E-04 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+52 s in the 8-1000 keV band
is 7.06 +/- 0.01 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 10978
Subject
GRB 100724B: Fermi LAT and GBM analysis
Date
2010-07-25T04:32:20Z (15 years ago)
From
James Chiang at SLAC <jchiang@slac.stanford.edu>
Yasuyuki Tanaka, Masanori Ohno (ISAS/JAXA), Hiromitsu Takahashi,
Takeshi Uehara (Hiroshima University), Nicola Omodei (Stanford Univ.),
James Chiang (SLAC) and Sylvain Guiriec (UAH) report on behalf of the
Fermi LAT and GBM teams:
At 00:42:06 UT on 24 July 2010, the Fermi Large Area Telescope (LAT)
detected gamma-rays from the long GRB 100724B. This burst was detected
and localized by the Fermi Gamma-Ray Burst Monitor (GBM) (trigger
301624927 / 100724029, GCN 10977).
The best LAT on-ground localization for this burst is RA, Dec =
120.04, 76.74 (08h 00m 09.6s, 76d 44' 24", J2000) with a 90%
containment radius of 1.1 degrees (statistical; 68% containment radius
0.6 degrees). At the GBM trigger time, this location was at angle of
49 degrees from the LAT boresight and approximately 18 degrees from
the Earth's limb. The GBM trigger caused an Autonomous Repoint
Request. However, owing to the proximity of the burst location to the
Earth horizon and constraints on the spacecraft pointing, the angle of
the source with respect to the boresight remained greater than 40
degrees for the first 2700 seconds after trigger.
Using a non-standard data selection designed to maximize the low
energy acceptance, the LAT light curve shows two distinct peaks at ~20
and ~64 s after the GBM trigger and a smaller sub-peak at ~77 s
post-trigger. A joint spectral fit with the GBM data yields a photon
index in the LAT band (> 20 MeV) of -2.48 +/- 0.01 (stat). This is
consistent with an extrapolation of the high energy part of the
spectrum in the GBM band. This result differs somewhat from the fit
reported in GCN 10977. In order to account for a spectral feature
below 100 keV, we have included a low energy spectral component in
addition to the usual Band function model; this accounts for the
difference found in the high energy photon index.
Further analysis is ongoing.
The Fermi LAT point of contact for this burst is Yasuyuki Tanaka
(tanaka@astro.isas.jaxa.jp).
The Fermi LAT is a pair conversion telescope designed to cover the
energy band from 20 MeV to greater than 300 GeV. It is the product of
an international collaboration between NASA and DOE in the U.S. and
many scientific institutions across France, Italy, Japan and Sweden.
[GCN OPS NOTE(24aug10): Per author's request, the date in the first line
was changed from "25 July" to "24 July".]
GCN Circular 10981
Subject
Konus-Wind observation of GRB 100724B
Date
2010-07-25T09:34:14Z (15 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 bright long hard GRB 100724B
(Fermi/GBM trigger 301624927: Bhat, GCN 10977;
localized by Fermi/LAT: Tanaka et al., GCN 10978)
triggered Konus-Wind at T0=2526.266s UT (00:42:06.266)
The burst light curve shows a complex structure with
a total duration of ~240 s. It consists of an initial harder part,
~90 s in duration, followed by a softer one, lasting to T0 + 230 s.
The emission is seen up to 10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB100724_T02526/
As observed by Konus-Wind the burst
had a fluence of 4.1(+/-0.3)x10-4 erg/cm2,
and a 256-ms peak flux, measured from T0+59.648s,
of 1.0(+/- 0.1)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+228.608 s) is best fit
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.87 (-0.06, +0.06),
the high energy photon index beta = -2.0 (-0.09, +0.07),
the peak energy Ep = 369(-37, +42)keV (chi2 = 86/87 dof).
The spectrum at the maximum count rate
(measured from T0+57.856 to T0+61.952 s) is best fit
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.8 (+/-0.1),
the high energy photon index beta = -2.1 (+/-0.15),
the peak energy Ep = 418(-58, +66)keV (chi2 = 84/87 dof).
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
GCN Circular 10994
Subject
GRB 100724B: gamma-ray detection by AGILE
Date
2010-07-26T14:36:30Z (15 years ago)
From
Martino Marisaldi at INAF-IASF <marisaldi@iasfbo.inaf.it>
M. Marisaldi, F. Fuschino, C. Labanti, M. Galli, A. Bulgarelli, F.
Gianotti, M. Trifoglio, G. Di Cocco (INAF/IASF Bologna), E. Del Monte,
I. Donnarumma, Y. Evangelista, M. Feroci, F. Lazzarotto, L. Pacciani, P.
Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IASF Rome), G.
Barbiellini, F. Longo, E. Moretti (INFN Trieste), A. Giuliani, A. Chen,
S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF Milan), M. Tavani, G.
Pucella, V. Vittorini, A. Argan, A. Trois, G. Piano, S. Sabatini
(INAF/IASF Rome), A. Pellizzoni, M. Pilia (INAF/OA Cagliari), S.
Vercellone, F. D'Ammando (INAF/IASF Palermo), P. W. Cattaneo, A.
Rappoldi (INFN Pavia), P. Picozza, A. Morselli, E. Striani, (INFN
Roma-2), M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari,
D. Zanello (INFN Roma-1), P. Giommi, C. Pittori, F. Lucarelli, P.
Santolamazza, F. Verrecchia (ASDC) and L. Salotti (ASI), on behalf of
the AGILE Team, report:
"The AGILE Gamma-Ray Imaging Detector (GRID) and Mini-Calorimeter (MCAL)
detected at gamma-ray energies the long bright GRB 100724B (Bhat, GCN
10977; Tanaka et al., GCN 10978; Golenetskii et al., GCN 10981).
The GRB triggered AGILE-MCAL, sensitive in the energy range 330 keV -
100 MeV, on 24 July 2010 at 00:42:00 UT (T0).
As seen by MCAL the burst has a duration (T90) of ~96 s, with observable
emission up to ~T0+150 s. The GRB emission has significant detection in
MCAL up to an energy of about 80 MeV.
The time integrated spectrum in the time interval [T0, T0+150.0 s]
can be fit in the energy range 500 keV - 80 MeV with a single powerlaw
with photon index -2.09 (-0.06, +0.08) (reduced chi2 = 0.94 with 39
d.o.f.). The estimated fluence is (2.7 � 0.2)x10-4 erg/cm2 in the same
energy range. All reported errors are at the 90% confidence level.
AGILE-GRID shows a definite detection above 100 MeV. Further analysis
are in progress.
This message may be cited."
GCN Circular 10995
Subject
GRB 100724B: Suzaku WAM observation of the prompt emission
Date
2010-07-26T15:09:31Z (15 years ago)
From
Takeshi Uehara at Hiroshima U <uehara@hirax7.hepl.hiroshima-u.ac.jp>
T. Uehara, Y. Hanabata, T. Takahashi, Y. Fukazawa (Hiroshima U.),
N. Vasquez (Tokyo Tech.) K. Yamaoka (Aoyama Gakuin U.), S. Sugita (Nagoya U.),
Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara, T. Yasuda (Saitama U.),
M. Ohno, M. Suzuki, M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa, T. Tamagawa (RIKEN), N. Ohmori, A. Daikyuji, Y. Nishioka,
M. Yamauchi (Univ. of Miyazaki), Y. Urata, H. M. Lin, P. Tsai (NCU),
K. Nakazawa, K. Makishima (Univ. of Tokyo),
S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report:
The bright long GRB 100724B (Fermi/GBM trigger #301624927 ; P. N. Bhat et al., GCN 10977)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 00:42:04.70 UT (=T0).
The observed light curve shows a multi-peaked structure starting at T0-7s, ending
at T0+143s with a duration (T90) of about 103 seconds.
The fluence in 100 - 1000 keV was 1.63(+0.03/-0.07) x 10^-4 erg/cm^2.
The 1-s peak flux measured from T0+65s was 9.3 photons/cm^2/s in the same
energy range.
Preliminary result shows that the time-averaged spectrum from
T0-4.1s to T0+141.3s is well fitted by a power-law with exponential cutoff model:
dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
alpha 1.09 (+0.18/-0.19), and
Epeak 666 (+107/-67) keV (chi^2/d.o.f. = 22.8/22).
All the quoted errors are at statistical 90% confidence level.
The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
The light curves with 1-sec time resolution for this burst will be appeared at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html
GCN Circular 10996
Subject
GRB 100724B: AGILE/GRID analysis
Date
2010-07-26T16:21:05Z (15 years ago)
From
Marco Feroci at IASF/INAF <sa.grb@iasf-roma.inaf.it>
A. Giuliani (INAF/IASF Milano), M. Tavani (INAF/IASF Roma), F. Longo
(INFN Trieste),
M. Marisaldi, F. Fuschino, C. Labanti, A. Bulgarelli, F. Gianotti, M.
Trifoglio, G. Di Cocco (INAF/IASF Bologna), M. Galli (ENEA), E. Del Monte,
I. Donnarumma, Y. Evangelista, M. Feroci, F. Lazzarotto, L. Pacciani,
P. Soffitta,
E. Costa, I. Lapshov, M. Rapisarda, A. Argan, G. Piano, G.
Pucella, S. Sabatini, E. Striani, A. Trois, V. Vittorini
(INAF/IASF Roma), A. Chen, S. Mereghetti, P. Caraveo, F.
Perotti (INAF/IASF Milano), A. Pellizzoni, M. Pilia (INAF/OA Cagliari),
F. D'Ammando, S. Vercellone (INAF/IASF Palermo), G. Barbiellini, E. Moretti,
E. Vallazza (INFN Trieste), A. Morselli, P. Picozza (INFN Roma-2),
M. Prest (Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1),
P.W. Cattaneo, A. Rappoldi (INFN Pavia), S. Cutini, C. Pittori, F. Verrecchia,
P. Santolamazza, F. Lucarelli and P. Giommi (ASDC), L. Salotti (ASI) report:
The Gamma-Ray Imaging Detector (GRID) on board AGILE detected the long
bright GRB 100724B (Bhat, GCN 10977; Tanaka et al., GCN 10978;
Golenetskii et al., GCN 10981, Marisaldi et al., GCN 10994)
in the energy range 25 - 500 MeV with a statistical significance
larger than 9 sigma.
The gamma-ray emission observed by the AGILE-GRID instrument lasted
about 100 seconds, and two peaks are evident in the lightcurve
consistent with the behaviour reported by Fermi LAT
(the MCAL and GRID preliminary lightcurves are available at
http://www.asdc.asi.it/images/GRB100724B_lc.gif ).
The total fluence above 25 MeV during this time interval is
F = 0.2+/-0.1 ph/cm2 .
A preliminary estimate of the gamma-ray spectral photon index is
alpha= 2.2 +/-0.3.
GRB 100724B turns out to be the brightest GRB detected by AGILE
above 100 MeV during its operations in space.
A plot showing the distance between the GRB position and the AGILE
boresight as a function of time can be retrieved at
http://www.asdc.asi.it/images/GRB_100724B_distance2.png .
This message may be cited.