GRB 120830A
GCN Circular 13704
Subject
GRB 120830A: Fermi-LAT detection of a short burst
Date
2012-08-30T22:21:58Z (13 years ago)
From
Giacomo Vianello at SLAC <giacomov@slac.stanford.edu>
G. Vianello (Stanford), J. Racusin (NASA/GSFC), and D. Donato (NASA/GFSC),
report on behalf of the Fermi-LAT team:
Fermi-LAT detected high energy emission from the short GRB 120830A in
ground analysis. The GRB triggered the Fermi-GBM on August 30th, 2012 at
07:07:03.53 UTC (trigger 368003226/120830297). At the time of the GBM
trigger, the angle between the GRB position and the LAT boresight was 38
degrees. The burst was also detected and localized through IPN, which will
be reported in an upcoming circular.
A preliminary maximum-likelihood analysis during the GBM T90 of the E>75MeV
P7TRANSIENT_V6 LAT data revealed a significantly detected transient source.
We obtain the best LAT on-ground localization of:
RA(J2000) = 88.42 deg
Dec(J2000) = -28.81 deg
with an error radius of 0.86 deg (68% containment, statistical error only),
which is 0.28 deg from the IPN position.
There were 4 photons above 100 MeV within 1 second of the GBM trigger
during the GBM emission. The highest energy photon is a 500 MeV event which
is observed 0.8 seconds after the GBM trigger. The likelihood fit provides
a photon index of 2.66 +/- 0.86, and a flux (100 MeV-10 GeV) over this
interval of 2.2e-07 +/- 1.7e-07 (erg/cm^2/s).
A Swift TOO has been requested based upon the IPN localization.
The Fermi LAT point of contact for this burst is Davide Donato (
davide.donato-1@nasa.gov).
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 Circular 13705
Subject
IPN Triangulation of short GRB 120830A
Date
2012-08-30T23:04:39Z (13 years ago)
From
Valerie Connaughton at UAH/NSSTC <valerie.connaughton@nasa.gov>
K. Hurley and J. Goldsten, on behalf of the MESSENGER GRNS 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,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and
V. Connaughton, M. S. Briggs, and C. Meegan, on behalf of the Fermi GBM team
report
The short-duration GRB, detected by the Fermi-LAT as reported in
GCN 13704 (Vianello, Racusin and Donato), was also observed so far
by MESSENGER (GRNS), Konus-Wind, INTEGRAL (SPI-ACS), and
Fermi GBM (trigger: 368003226).
We have triangulated the burst to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
88.649 (05h 54m 36s) -28.984 (-28d 59' 04")
Corners:
88.489 (05h 53m 57s) -28.613 (-28d 36' 49")
88.480 (05h 53m 55s) -28.808 (-28d 48' 29")
88.810 (05h 55m 14s) -29.353 (-29d 21' 12")
88.818 (05h 55m 16s) -29.160 (-29d 09' 36")
---------------------------------------------
The error box area is 215 sq. arcmin, its maximum dimension is 47 arcmin,
and it is fully contained within the LAT error circle.
A Swift ToO has been approved.
This box can be improved.
A triangulation map showing the error box and the LAT error circle is posted at
http://gammaray.nsstc.nasa.gov/gbm/science/ipn_plots/loc_ipn_lat_120830297.pdf
The time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular 13706
Subject
GRB 120830A: early MASTER optical limit
Date
2012-08-31T09:07:25Z (13 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
H. Levato and C. Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)
C. Mallamaci, C. Lopez and F. Podest
Observatorio Astronomico Felix Aguilar (OAFA)
E. Gorbovskoy, V. Lipunov, V. Kornilov, D. Denisenko, A. Kuznetsov,
D. Kuvshinov, A. Belinski, N. Tyurina, N. Shatskiy, P. Balanutsa, D. Zimnukhov,
V.V. Chazov
Lomonosov Moscow State University, Sternberg Astronomical Institute
A. Tlatov, A.V. Parhomenko, D. Dormidontov, V. Sennik
Kislovodsk Solar Station of the Pulkovo Observatory
K. Ivanov, S. Yazev, N.M. Budnev, O. Gres, O. Chuvalaev, V.A. Poleshchuk
Irkutsk State University
V. Yurkov, Yu. Sergienko, D. Varda, E. Sinyakov
Blagoveschensk Educational State University, Blagoveschensk
V. Krushinski, I. Zalozhnich, A. Popov, A. Bourdanov, A. Punanova
Ural Federal University
MASTER-ICATE robotic very wide field cameras (FOV=2x384 square degrees, D=72mm,
f/1.2, 1 pix = 22 arcsec, http://observ.pereplet.ru) located in Argentina
(Observatorio Astronomico Felix Aguilar, http://93.180.27.230:8080/) were
pointed to the FERMI GRB120830A (Vianello et al., GCN 13704) 18 s after
notice time and 44 s after GRB time at 2012-08-30 07:07:47 UT(Levato et al., GCN 13703).
We cover IPN (Hurley et al., GCN 13705) and Fermi LAT error boxes.
We haven`t found optical transient on our first (5 s
exposure) set and on coadd image made of 60 images and complete exposure of 300
seconds.
The coverage map is available
http://master.sai.msu.ru/static/GRB120830A_IPN_LAT.jpeg
The 5-sigma upper limit on single image has been about 11.0 mag and 12.0 mag
on coadd image.
Our cameras are continuously imaging the sky with 5 sec exposures.
Weather conditions were not so good (feeble cloudiness).
This message can be cited.
GCN Circular 13707
Subject
Konus-Wind observation of GRB 120830A
Date
2012-08-31T10:57:46Z (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 short-duration hard-spectrum GRB 120830A
(Fermi-LAT detection: Vianello et al., GCN 13704;
IPN localization: Hurley at al., GCN 13705)
triggered Konus-Wind at T0=25623.562s UT (07:07:03.562)
The light curve shows a single pulse with a duration of ~0.9 s.
The emission 2is seen up to ~5 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB120830_T25623/
As observed by Konus-Wind the burst
had a fluence of 4.8(-0.7,+1.1)x10-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.080 s,
of 1.6(-0.5,+0.5)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured T0 to T0+0.256 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model, for which
alpha = 0.25 (-0.35, +0.45),
and Ep = 1070(-200, +240) keV,
chi2 = 27/22 dof.
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
GCN Circular 13708
Subject
GRB 120830A: Fermi GBM observation
Date
2012-08-31T18:12:23Z (13 years ago)
From
David Tierney at UCD <david.tierney@ucd.ie>
D. Tierney (UCD)
reports on behalf of the Fermi GBM Team:
"At 07:07:03.53 UT on 30 August 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120830A (trigger 368003226 / 120830297).
The burst was located by the Fermi LAT
(G. Vianello et al. 2012, GCN 13704) and
the IPN (Hurley at al. 2012, GCN 13705)
The burst was also independently detected by
Konus-Wind (S. Golenetskii et al. 2012, GCN 13707).
and by INTEGRAL SPI-ACS.
The GBM light curve consists of a single peak
with a duration (T90) of 1.28 +/- 0.23 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+1.088 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.40 (+0.08/-0.07) and
the cutoff energy, parameterized as Epeak,
is 1214.00 (+155.00/-133.00) keV
The event fluence (10-1000 keV) in this time interval is
(3.253 +/- 0.113)E-06 erg/cm^2. The 64 ms peak photon flux measured
starting from T0+0.128 s in the 10-1000 keV band
is 10.07 +/- 0.89 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 1212.00 (+140.00/-140.00) keV, alpha = -0.40 (+0.08/-0.07)
and an upper limit on beta (2 sigma error) = -4.35 (+2.46)
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 13709
Subject
GRB 120830A: Swift-XRT and UVOT observations
Date
2012-08-31T18:43:14Z (13 years ago)
From
Wayne Baumgartner at GSFC <wayne@milkyway.gsfc.nasa.gov>
W. H. Baumgartner (GSFC/UMBC), V. D'Elia (ASDC), M. Siegel (PSU),
F. E. Marshall (NASA/GSFC), J. L. Racusin (NASA/GSFC), J. A. Kennea
(PSU), and D. N. Burrows (PSU) report on behalf of the Swift team:
Swift observed the the error circle for the Fermi/LAT and IPN detected
GRB 120831A (Vianello et al., GCN Circ. 13704, Hurley et al. GCN Circ
13705). Two 4 ks XRT observations were taken to cover the IPN error
region, beginning about 60 ks and 72 ks after the burst. Together
these two XRT observations cover 100% of the IPN error box.
One uncatologed X-ray source is found within the IPN error box at RA,
Dec = 88.501667, -28.701333 which is equivalent to:
RA (J2000): 05h 54m 00.40s
Dec (J2000): -28d 42' 04.8"
with an uncertainty of 8 arcsec (radius, 90% confidence). The XRT
source has a significance of 2.5 sigma, and the count rate during this
observation in photon counting mode was 2.53e-3 +/- 1.0e-3 cts sec^-1.
The Swift/UVOT began settled observations of the first of the two
fields for GRB 120830A 59804 s after the LAT/IPN trigger. No data are
available yet for the second field. A source consistent with the XRT
source is detected in the initial UVOT exposures. There is no
corresponding source in the USNO-B1.0 catalog.
The preliminary UVOT position is:
RA (J2000) = 05:54:00.65 = 88.50270 (deg.)
Dec (J2000) = -28:42:06.4 = -28.70178 (deg.)
with an estimated uncertainty of 0.55 arc sec. (radius, 90% confidence).
Preliminary results using the UVOT photometric system (Breeveld et
al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 59804 67310 3679 20.42 +/- 0.04
The magnitude in the table is not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.032 in the direction of the burst
(Schlegel et al. 1998).
There is no convincing evidence for UVOT variability of the source.
Further Swift observations are planned to determine whether the source
is fading.
GCN Circular 13710
Subject
GRB 120830A: catalog source at Uvot position
Date
2012-09-01T09:28:23Z (13 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
Vladimir Lipunov, Lomonosov Moscow State University, SAI
There is one infrared source at Swift Uvot OT canddate position
(Baumgartner et al., GCN 13709) in WISE All-Sky data Release J055400.58-284205 with 0.9 arcsec
offset.
There is one nonstar object (Jmag = 22.3)in the Guide Star Catalog with
offset 0.1 arcsec.
Both objects may be same.
This message can be cited.
GCN Circular 13711
Subject
GRB 120830A: Further Swift Observations
Date
2012-09-01T16:41:42Z (13 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC), V. D'Elia (ASDC), M. Siegel (PSU),
and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift team:
Swift observed again the Fermi/LAT-detected GRB 120830A (Vianello et
al., GCN Circ. 13704; Hurley et al., GCN Circ 13705).
A new 4 ks XRT observation was taken to check for variability of the
source reported in Baumgartner et al. (GCN Circ. 13709). The
observation began about 129 ks after the burst. The x-ray source previously
detected at low confidence with a count rate of (2.53 +/- 1.0)e-3
cts/s is no longer detected with a three sigma upper limit of
2.18e-03 cts/s.
UVOT made a second observation of GRB 120830A starting
129 ks after the LAT/IPN trigger. The flux of the UVOT source
previously detected has not changed, indicating
that it is unlikely to be the afterglow of the GRB.
As noted by Lipunov (GCN Circ. 13710), the
source position is consistent with a WISE catalogued source.
Preliminary results using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 59804 67310 3679 20.42 +/- 0.04
white 128849 136335 3883 20.43 +/- 0.04
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.032 in the direction of the burst
(Schlegel et al. 1998).