GRB 090516A, GRB 090516
GCN Circular 9422
Subject
GRB 090516A: Konus-Wind and Swift/BAT joint spectral analysis
Date
2009-05-24T17:27:29Z (17 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori.sakamoto-1@nasa.gov>
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC),
W. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD),
D. Palmer (LANL), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), and T. Ukwatta (GWU)
V. Pal'shin, S. Golenetskii, R.Aptekar, E. Mazets, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team,
report:
We performed the Konus-Wind and the Swift/BAT joint spectral analysis
of GRB 090516A (Swift/BAT trigger #352190: Rowlinson et al., GCN Circ.
9374, Baumgartner et al. GCN Circ. 9384). Since the Konus-Wind observed
this GRB in the waiting mode, we only have 3 channel spectral data for
the Konus-Wind which cover the energy range from 20 keV to 1.2 MeV. The
joint spectral analysis of the Konus-Wind and the Swift/BAT data
allows us to derive the broad-band spectral parameters of this burst.
The time interval of the spectral data for each instrument is chosen
from T0(BAT)-12.2 to T0(BAT)+96.7 sec where T0(BAT) is the trigger time
of BAT at 08:27:50.8 UTC. The energy ranges which we used in the joint
spectral analysis are 20-1200 keV and 14-150 keV for the Konus-Wind and
the Swift/BAT respectively. The spectral data of two instruments are
fitted with the spectral model multiplied by the constant factor to take
into account the systematic effective area uncertainties in the response
matrices of each instrument.
The spectrum is well fitted with a power-law with exponential cutoff
model: dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). The constant factors
of each instrument agree within 10%. No systematic residual from the
best fit model is seen in the spectral data of each instrument. The
best fit spectral parameters are: alpha = -1.5 (-0.3/+0.2) and Epeak
= 190 (-65/+230) keV (chi2/dof = 54/56). The best fit spectral
parameters for the GRB (Band) model fixing beta = -2.5 are:
alpha = -1.5 (-0.2/+0.3), and Epeak = 190 (-75/+270) keV (chi2/dof = 55/56).
The energy fluence in the 15-1200 keV band calculated by a power-law
with exponential cutoff model for this 107.9 sec interval is
(1.5 +/- 0.3)x10^-5 erg/cm2.
Assuming z = 4.109 (de Ugarte Postigo et al. GCN Circ. 9383) and a standard
cosmology model with H_0 = 71 km/s/Mpc, Omega_M = 0.27, Omega_Lambda =
0.73, the isotropic energy release is E_iso = 6.5 (-1.1/+1.4) x10^53 erg in
1 keV to 10 MeV at the GRB rest frame extrapolating the best Band function fit
fixing beta = -2.5.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB090516/
All the quoted errors are at the 90% confidence level.
GCN Circular 9415
Subject
GRB 090516: Fermi GBM observation
Date
2009-05-21T08:51:16Z (17 years ago)
From
Sheila McBreen at MPE <smcbreen@mpe.mpg.de>
Sheila McBreen (UCD/MPE)
reports on behalf of the Fermi GBM Team:
"At 08:27:58.35 UT on 16 May 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090516 (trigger 264155280 / 090516353).
which was also detected by the Swift-BAT
(Rowlinson et al. 2009, GCN 9374).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 20 degrees.
The GBM light curve consists of about five overlapping
pulses from T0-50 s to T+120 s. There is continued weak emission
until about T0+300 s (8-1000 keV).
Due to a large change in the spacecraft pointing during this long
burst, a time averaged spectrum could not be fit. Instead three
spectral intervals from -50 to 20 sec, 20 to 60 sec
and 60 to 120 seconds were selected.
The first interval was well fit by a power law function with
an exponential high energy cutoff. The power law index
is -1.51 ( +/-0.11 ) and the cutoff energy, parameterized as
Epeak, is 185.6 (+98.4/-42.5) keV.
The second and third intervals are adequately fit by a Band function.
The parameters for interval two are alpha = -1.03 (+0.26/-0.31) ,
Epeak = 51.4 (+20.1, -11.4), beta= -2.1 ( +0.1/-0.2)
and for the third interval, alpha = 0.30 (+1.30/ - 0.78),
Epeak = 27.87 +/- 5.0), beta = -2.64 +/-0.4.
The sum of the event fluence (8-1000 keV) in these time intervals is
(2.3 +/- 0.5)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+28.6 s in the 8-1000 keV band
is 5.3 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 9396
Subject
GRB 090516: Observations from Stardome Observatory
Date
2009-05-19T06:10:37Z (17 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
G. W. Christie (Stardome, New Zealand), A. de Ugarte Postigo
(ESO, Chile) and T. Natusch (Stardome, New Zealand) on
behalf of a larger collaboration report:
We observed the field of GRB 090516 (Rowlinson et al. GCN
9374) with the Stardome 0.4m telescope located in Auckland
(New Zealand) starting at 09:25UT. We used a SG530 filter
that transmits wavelengths above 5300 Angstroms and a SBIG
ST-L-6303E CCD (KAF-6303E detector). A 9x300s combined
exposure with mean epoch 16.4080 May (80 minutes after the
burst) shows an object at the position of the afterglow
(Guidorzi et al. GCN 9375) measured at R = 20.8 +/- 0.2 as
compared to USNO-B1.0 stars. We note that with the GRB at
a redshift of 4.1 (de Ugarte Postigo et al. GCN 9383),
Ly-alpha falls within the R-band, so that comparison of
clear and very broad band filters such as ours with R-band
has to be handled with care.
GCN Circular 9391
Subject
GRB 090516, RIMOTS optical upper limits
Date
2009-05-18T13:29:42Z (17 years ago)
From
Norisuke Ohmori at Miyazaki U <ohmori@astro.miyazaki-u.ac.jp>
N. Ohmori, E. Sonoda, K. Kono, H. hayasi,
A. Daikyuji, Y. Nisioka, K. Noda, M. Yamauchi
(University of Miyazaki)
We have observed the field covering the error circle of
GRB090516 (Swift trigger 352190, GCN 9374, Rowlinson et al.)
with the unfiltered CCD camera on the 30-cm telescope
at University of Miyazaki.
The observation was started 11:16:08 UT (1.8 hr after the Swift trigger),
under cloudy condition.
First image was obtained at 11:17:11 UT (1.8 hr after the Swift trigger).
We have compared our data of 30 sec exposures with the USNO-A2.0 catalog.
There is no new source at the reported position.
(GCN 9374, B. A. Rowlinson et al. GCN 9375, C. Guidorzi et al.
GCN 9376, A. P. Beardmore et al. GCN 9379, J. Gorosabel et al.
GCN 9381, A. de Ugarte Postigo et al.)
the upper limits are as follows:
---------------------------------------------------------------
Start(UT) End(UT) Num. of frames Limit (mag.)
---------------------------------------------------------------
11:16:08 11:17:11 1 15.6
11:16:08 12:04:00 21 17.7
---------------------------------------------------------------
GCN Circular 9384
Subject
GRB 090516: Swift-BAT refined analysis
Date
2009-05-17T16:59:56Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), B. A. Rowlinson (U Leicester),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090516 (trigger #352190)
(Rowlings, et al., GCN Circ. 9374