Gamma-ray Burst 100707A
(All information courtesy of the instrument teams.)
Previous IAU Circulars
Results of Observations
- GCN Circular #10944
Colleen A. Wilson-Hodge (NASA/MSFC) and Suzanne Foley (MPE)
report on behalf of the Fermi GBM Team:
"At 00:46:38.99 UT on 07 July 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100707 (trigger 300156400 / 100707.032).
The on-ground calculated location, using the GBM trigger
data, is RA = 351.07, DEC = -6.57 (J2000 degrees,
equivalent to 23 h 24 m, -6 d 34 '), with an uncertainty
of 1 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 90 degrees.
The GBM light curve show a fast rise and exponential decay
with a duration (T90) of 82+/-1 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+83.009 s is
well fit by a power law function with an exponential
high energy cutoff. The power law index is -0.91 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 283 +/- 7 keV
(C-Statistic 529.4 for 358 d.o.f.).
The event fluence (10-1000 keV) in this time interval is
(8.77 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.152 s in the 10-1000 keV band
is 48.3 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #10945
Veronique Pelassa (LPTA), Melissa Pesce-Rollins (INFN-Pisa) report on
behalf of the Fermi LAT collaboration:
The Fermi Large Area Telescope (LAT) detected emission from GRB
100707A (C. Wilson-Hodge et al, GCN 10944).
This burst was at an angle of 90 degrees to the LAT boresight, which
means that neither directional nor energy information can be obtained
with the standard analysis procedures.
Using a non-standard data selection, the LAT light curve shows a
single, sharply rising pulse that has a somewhat more gradual decay,
similar to the initial peak in the GBM light curve. The LAT T90
duration is <30 s. This is shorter than the GBM T90 (82+/-1 s), but
the LAT may be missing a long tail at later times owing to noisier
data. Over 300 counts above background were detected within a 5 s
interval in coincidence with the main GBM peak. The significance of
this excess was greater than 14 sigma. A preliminary study of the
instrument performance at such a large inclination suggests that these
events are likely to be low energy gamma-rays, with energies less than
Further analysis is ongoing.
The Fermi LAT point of contact for this burst is Veronique Pelassa
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.
This message can be cited.
- GCN Circular #10947
K. Hurley and J. Goldsten, on behalf of the MESSENGER GRNS GRB
S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P.
Oleynik, M. Ulanov, D. Svinkin and T. Cline on behalf of the Konus-Wind
V. Connaughton, M.S. Briggs, and C.A. Meegan on behalf of the Fermi
GBM team, and
K. Yamaoka, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada,
T. Murakami, K. Makishima, and Y. Hanabata on behalf of the Suzaku-WAM
The long bright GRB 100707A, observed by Fermi/GBM at 00:46:38.99 UT
(Wilson-Hodge & Foley, GCN 10944) and Fermi/LAT (Pelassa &
Pesce-Rollins, GCN 10945), has also been detected by Suzaku (WAM),
Konus-Wind, and MESSENGER (GRNS) so far.
We have triangulated it to a preliminary 3 sigma error box whose
RA(2000), deg Dec(2000), deg
358.019 (23h 52m 05s) -8.658 (-08d 39' 29")
358.562 (23h 54m 15s) -11.226 (-11d 13' 32")
358.773 (23h 55m 05s) -11.654 (-11d 39' 14")
357.369 (23h 49m 29s) -5.832 (-05d 49' 56")
357.116 (23h 48m 28s) -5.295 (-05d 17' 42")
The error box area is 0.660 sq. deg
This error box may be improved.
The GBM position (Wilson-Hodge & Foley, GCN 10944) is 7.2 deg from the
center of the box.
- GCN Circular #10948
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 very bright long GRB 100707A
(Fermi/GBM trigger 300156400: Wilson-Hodge and Foley, GCN 10944;
localized by IPN: Hurley et al., GCN 10947)
triggered Konus-Wind at T0=2798.855s UT (00:46:38.855)
The burst light curve consists of a single FRED pulse
with a duration of ~100 s.
The Konus-Wind light curve of this GRB is available at
The periodic dips seen in the 64-ms lc are caused
by the occultation of the Konus detector
by other instrument on board the rotating Wind s/c.
As observed by Konus-Wind the burst
had a fluence of 8.8(+/-0.6)x10-5 erg/cm2,
and a 64-ms peak flux measured from T0+1.344s
of 2.4(+/- 0.2)x10-5 erg/cm2/s
(both in the 20 keV - 2 MeV energy range).
The time-integrated spectrum of the burst
(from T0 to T0+102.144 s) is best fit
in the 20 keV - 2 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.95 (+/-0.15),
the high energy photon index beta = -2.2 (-0.3, +0.2),
the peak energy Ep = 264(-40, +49)keV (chi2 = 43.5/57 dof).
The spectrum at the maximum count rate
(measured from T0+1.280 to T0+1.792 s) is best fit
in the 20 keV - 2 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = +0.3 (-0.3, +0.5),
the high energy photon index beta = -2.4 (-0.5, +0.3),
the peak energy Ep = 383(-82, +80)keV (chi2 = 53.2/57 dof).
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
- GCN Circular #10950
Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa (Hiroshima U.)
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), N. Vasquez (Tokyo Tech.), Y. Urata,
H. M. Lin (NCU), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo),
S. Hong (Nihon U.), on behalf of the Suzaku WAM team, report:
The long GRB 100707A (Fermi/GBM trigger #300156400; C. Wilson-Hodge et al.,
GCN 10944; Fermi-LAT detection; V. Pelassa et al., GCN 10945)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy of 50 keV - 5 MeV at 2010-07-07 00:46:38.91 UT (T=0).
The observed light curve shows a FRED-like peak structure lasting from
T0-0.5s to T0+18.5s with T90 of about 12 seconds. The fluence in 100 -
1000 keV was 5.26 (+/-0.27) x 10^-5 erg/cm^2. The 1-s peak flux
measured from T0+1.5s was 32.24 (-1.28, +1.22) photons/cm^2/s in the
same energy range.
Preliminary result shows that the time-averaged spectrum from T0-0.5s
to T0+18.5s is well fitted by a single power-law with a photon index
of 2.15 (-0.05, +0.06) (chi^2/d.o.f = 39.4/25).
Due to the brightness of this burst, a 3% systematic error was added
for low energy channels. In addition, there might be some calibration
uncertainties in these spectral parameters because GRB photons came to
the WAM detector by passing through the large Ne dewar of the X-ray
All the errors are quoted at 90% confidence level.
The light curves for this burst wiil be available at:
- 1110.4246 from 20 Oct 11
Makoto S. Tashiro et al.: Spectral Evolutions in Gamma-Ray Burst Exponential Decays Observed with Suzaku WAM
This paper presents a study on the spectral evolution of gamma-ray burst (GRB) prompt emissions observed with the Suzaku Wide-band All-sky
Monitor (WAM). By making use of the WAM data archive, 6 bright GRBs exhibiting 7 well-separated fast-rise-exponential-decay (FRED) shaped light
curves are presented and the evaluated exponential decay time constants of the energy-resolved light curves from these FRED peak light curves
are shown to indicate significant spectral evolution. The energy dependence of the time constants is well described with a power-law function
tau(E) ~ E^gamma, where gamma ~ -(0.34 +/- 0.12) in average, although 5 FRED peaks show consistent value of gamma = -1/2 which is expected in
synchrotron or inverse-Compton cooling models. In particular, 2 of the GRBs were located with accuracy sufficient to evaluate the time-resolved
spectra with precise energy response matrices. Their behavior in spectral evolution suggests two different origins of emissions. In the case of
GRB081224, the derived 1-s time-resolved spectra are well described by a blackbody radiation model with a power-law component. The derived
behavior of cooling is consistent with that expected from radiative cooling or expansion of the emission region. On the other hand, the other
1-s time-resolved spectra from GRB100707A is well described by a Band GRB model as well as with the thermal model. Although relative poor
statistics prevent us to conclude, the energy dependence in decaying light curve is consistent with that expected in the former emission
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Jochen Greiner, last update: 20-Oct-2011