- GCN Circular #14282
S. Guiriec (NASA/GSFC/NPP), G. Vianello (Stanford)
and M. Ohno (Hiroshima U.)
report on behalf of the Fermi-LAT team:
The Fermi Large Area Telescope (LAT) detected emission from
GRB 130310A (GBM trigger 130310840/384638984) at approximately
20:09:44 UT on March 10th, 2013, about 3s after Fermi-GBM trigger time.
The burst location was outside the LAT nominal field of view, at an angle
of ~79 degrees from the LAT boresight, and ~50 degrees from the Zenith.
Using the non-standard LAT Low Energy (LLE) data selection, featuring
a large effective area and a larger field of view below 100 MeV but a much
larger PSF with respect to the standard classes, we clearly detect
the prompt emission of the GRB (significance > 10 sigma above the
background). With this selection and in this energy range the GRB shows
a single FRED-like pulse, peaking ~3 s after the GBM trigger in good
coincidence with the peak of the GBM emission.
The high peak flux of the burst triggered an Autonomous Repointing
Request (ARR) starting about 50s after the trigger time, which placed
the GRB within the LAT nominal field of view for standard data
classes (~65 deg) approximately 200 s after the trigger.
Using the P7SOURCE_V6 class we detect ~18 photons between 100 MeV
and 3 GeV in the time interval 200 s - 800 s from the trigger, clearly clustered
in a point source ~4.8 deg away from the best GBM position and with
a significance larger than 5 sigma. Our best localization is:
R.A., Dec = 142.34, -17.23 (J2000)
90 % containment radius (statistical only) = 0.45 deg.
A GBM circular on GRB 130310A is forthcoming.
The Fermi LAT point of contact for this burst is Sylvain Guiriec
(sylvain.guiriec@nasa.gov)
- GCN Circular #14283
Shaolin Xiong (UAH) and Vandiver Chaplin (UAH)
report on behalf of the Fermi GBM Team:
"At 20:09:41.50 UT on 10 March 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130310A (trigger 384638984 / 130310840),
which was also detected by the Fermi/LAT (Guiriec et al. 2013, GCN 14282)
The GBM on-ground location is consistent with the LAT position.
At the time of triggering the angle from the Fermi LAT boresight was
79 degrees. GBM generated a Autonomous Repointing
Request (ARR) due to the high peak flux of this GRB, causing
Fermi to reorient so that the LAT could better observe this GRB.
The GBM light curve consists of a precursor and a FRED pulse
with a duration (T90) of about 2.4 s (50-300 keV).
The time-averaged spectrum from T0+4.1 s to T0+5.0 s is
adequately fit by a Band function with Epeak = 2.1 +/- 0.2 MeV,
alpha = -1.01 +/- 0.02, and beta = -2.27 +/- 0.1.
The event fluence (10-1000 keV) in this time interval is
(1.4 +/- 0.02)E-5 erg/cm^2. The 0.064 sec peak photon flux measured
starting from T0+4.1 s in the 10-1000 keV band is 170 +/- 3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #14284
S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
K. Hurley and J. Goldsten, on behalf of MESSENGER GRNS GRB team,
I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,
V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi
GBM team,
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, and
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:
The short-duration, hard-spectrum, intense GRB 130310A (Fermi/LAT
detection: Guiriec, Vianello, Ohno, GCN 14282; Fermi/GBM detection:
Xiong and Chaplin, GCN 14283) has been also observed by Konus-Wind,
Suzaku (WAM), INTEGRAL (SPI-ACS), MESSENGER (GRNS), and Mars Odyssey
(HEND), so far, at about 72585 s UT (20:09:45).
We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
141.905 (09h 27m 37s) -17.431 (-17d 25' 53")
Corners:
141.722 (09h 26m 53s) -16.780 (-16d 46' 50")
141.801 (09h 27m 12s) -17.435 (-17d 26' 06")
142.093 (09h 28m 22s) -18.072 (-18d 04' 18")
142.008 (09h 28m 02s) -17.428 (-17d 25' 40")
---------------------------------------------
The error box area is 465 sq. arcmin, and its maximum
dimension is 80 arcmin (the minimum one is 12 arcmin; the minimum
annulus width is 11 arcmin).
This box can be improved.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB130310_T72588/IPN/
The center of the LAT position (Guiriec, Vianello, Ohno, GCN 14282) is
0.46 deg from the box center.
- GCN Circular #14285
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 hard intense GRB 130310A
(Fermi-LAT detection: Guiriec et al., GCN 14282;
Fermi-GBM detection: Xiong and Chaplin, GCN 14283
IPN triangulation: Golenetskii et al., GCN 14284)
triggered Konus-Wind at T0=3D72588.897s UT (20:09:48.897)
The light curve shows a bright hard FRED-like structure
with a total duration of ~3 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/GRB130310_T72588/
As observed by Konus-Wind, the burst
had a fluence of (3.0 =B1 0.3)x10-5 erg/cm2,
and a 16-ms peak flux, measured from T0+0.000s,
of (3.6 =B1 0.2)x10-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha =3D -1.03 =B1 0.05,
the high energy photon index beta =3D -1.85 =B1 0.15,
the peak energy Ep =3D 855 =B1 270 keV,
chi2 =3D 85.8/97 dof.
The spectrum at the maximum count rate (measured from T0 to T0+0.064 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha =3D -0.87 =B1 0.13,
the high energy photon index beta =3D -1.62 =B1 0.28,
the peak energy Ep =3D 2600 =B1 1400 keV,
chi2 =3D 27.9/26 dof.
All the quoted results are preliminary.
- GCN Circular #14288
B. Sbarufatti (INAF-OAB/PSU), D. N. Burrows (PSU), J. L. Racusin
(NASA/GSFC), C. J. Mountford (U Leicester), N. Gehrels (NASA/GSFC) report
on behalf of the Swift team:
Swift performed 3 pointings of 1.5 ks each to cover the IPN error box for
GRB 130310A (Golenetskii et al., GCN #14284). A single, uncatalogued
source is detected at coordinates:
RA/Dec (J2000) = 09 27 36.35 -17 06 16.1
RA/Dec (J2000) = 141.901 -17.1044
Error radius (arcsec) = 3.6 (90% confidence level)
The source is inside the IPN error box, and 0.44 degrees from the Fermi
LAT position (Guiriec et al., GCN #14282), just inside the LAT error
circle.
The countrate is 7.60E-03 +/- 2.5E-03 c/sec
At present is not possible to tell if the source is fading.
This circular is an official product of the Swift-XRT team.
- GCN Circular #14289
A. Cucchiara (UCSC/UCO Lick Observatory), S. B. Cenko
(UC Berkeley), D. Perley (Caltech) report on behalf of
a large collaboration:
"On March 12.4 UT we observed the field of the short-hard
GRB 130313A (GCN 14282, 14283, 14284, 14285 and 14288)
with the Gemini-South telescope equipped with the GMOS camera.
We obtained 5x180s exposures, for a total integration time
of 15 minutes (T_mid = T0+1.22 days).
A snapshot of our imaging campaign can be seen here:
https://www.dropbox.com/s/jqt714c44b7ngei/0310A_rband.jpeg
We note the presence of two irregular objects (marked as "G1" adn "G2")
within the current XRT error circle (3.6 arcsec radius, GCN 14288).
The coordinates of this objects are:
"G1"
RA: 09:27:36.34 (J2000)
Dec: -17:06:18.92 (J2000)
"G2"
RA: 09:27:36.46 (J2000)
Dec: -17:06:13.80 (J2000)
Using 3 USNO-B1 stars we estimate a preliminary
brightness for "G1" of r' = 25.05 +- 0.15 and for
"G2" r'=23.80 +- 0.10.
At this point the nature of these objects as well as the relation with
GRB 130313A afterglow is still uncertain. Further observations
are encouraged.
We thank the Gemini staff for performing this observations,
in particular J. Thomas-Osip"
- GCN Circular #14290
B. Sbarufatti (INAF-OAB/PSU), D. N. Burrows (PSU), P. E. Evans (U
Leicester), E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift team:
Upon further analysis of the Swift XRT observations of the IPN error box
for GRB 130310A (Svinkin et al., GCN #14284) we RETRACT the detection of a
candidate afterglow reported by Sbarufatti et al., GCN #14288.
Further analysis is ongoing.
This circular is an official product of the Swift-XRT team.
- GCN Circular #14310
T. Kawano, M. Ohno, Y. Hanabata, Y. Tanaka, R. Nakamura, K. Takaki,
Y. Fukazawa (Hiroshima U.),
A. Sakamoto, M. Tashiro, Y. Terada, W. Iwakiri, T. Yasuda, K. Takahara,
M. Asahina, S. Kobayashi, H. Ueno (Saitama U.),
M. Akiyama, N. Ohmori, M. Yamauchi (Univ. of Miyazaki),
Y. E. Nakagawa (Waseda U.), S. Sugita (Nagoya U.), K. Yamaoka,
M. Kokubun, T. Takahashi (ISAS/JAXA), Y. Urata, P. Tsai (NCU), K. Nakazawa,
K. Makishima (Univ. of Tokyo), on behalf of the Suzaku WAM team, report:
The bright short GRB (Fermi-LAT detection ; Guiriec et al., GCN14282;
Sbarufatti et al., GCN 14288) triggered by the Suzaku Wide-band All-sky
Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 20:09:45 UT (=T0).
The observed light curve shows a single peak structure starting at
T0 s, ending at T0+1 s with a duration (T90) of about 0.3 seconds.
The fluence in 100 - 1000 keV was 7.78 (-1.13, +2.72) x 10^-6 erg/cm^2.
The 1-s peak flux measured from T0 s was 14.34(-1.37,+2.30)
photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0 to
T0+1 s is well fitted by GRB Band model:
the low-energy photon index alpha: -1.13 (-0.25, +0.16),
beta : -2.07 (-0.32, +0.19)
and the peak energy Epeak: 1000 (-442, +639) keV (chi^2/d.o.f = 43.2/44).
All the quoted errors are at statistical 90% confidence level.
The light curves for this burst will be available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html
- GCN Circular #14316
B. Sbarufatti (INAF-OAB/PSU), D. N. Burrows (PSU), P. E. Evans (U
Leicester) report on behalf of the Swift XRT team:
Swift performed a total of 7 pointings for this burst on March 11th: 4x1ks
covering the Fermi LAT error circle (Guiriec et al., GCN #1482) and 3x1.5
ks covering the IPN error box (Golenetskii et al., GCN #14284). We detect
a total of 5 sources:
# RA DEC Err counts rate(counts/ks)
1 09 28 45.9 -17 18 49.5 7.4" 9 11 (+11/-7)
2 09 29 27.0 -17 30 13.8 6.8" 12 13 (+14/-8)
3 09 28 59.0 -17 00 40.8 5.4" 8 9 (+10/-7)
4 09 27 58.9 -17 12 57.9 8.6" 10 11 (+12/-7)
5 09 27 31.7 -17 08 55.3 11.0" 5 4.7 (+6/-4)
The fluxes are computed at the 99% confidence level, following Kraft,
Burrows & Nousek (1991). The background level was computed both generally,
using the 'background' task of XIMAGE on each pointing, and locally, using
the 'sosta' task of XIMAGE, and selecting the highest value.
All sources are inside the LAT error circle, but only source #5 is inside
the IPN error box.
Swift performed another observation in the direction of source #5 on March
13th, with a 3.4 ks exposure. The 99% confidence level upper limit at the
position of source #5 is 4.6E-3 counts/s, which does not give strong
evidence for fading.
No further observations are planned.
This circular is an official product of the Swift-XRT team.
- GCN Circular #14350
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), Jos=E9 A. de Diego (UNAM),
Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM),
Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report:
We observed the field of the Fermi-LAT detected GRB 130310A (Guiriec, et
al., GCN 14282) with the Reionization and Transients Infrared Camera
(RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the
Observatorio Astron=F3mico Nacional on Sierra San Pedro M=E1rtir. Data w=
ere
taken in the r' and i' channels for a central 9.8 x 7.3 arcmin^2 portion =
of
the IPN error region (Golenetskii, et al., GCN 14284), centered on RA, DE=
C
=3D 141.90061, -17.10809 (J2000), in 2 epochs, 1.31-1.47 days after the
Fermi trigger and 3.31-3.45 days after the Fermi trigger. We reach a
limiting magnitude ~24 (AB) in both channels in both epochs. Data were
captured in the Z, Y, J, and H bands over a larger field (14.8 x 12.5
arcmin^2), reaching a shallower limit (~22 AB).
Of the XRT candidate afterglows (Sbarufatti, et al., GCN 14316), only
source #5 is contained in our images. We detect that source in both epochs
at a position RA, DEC =3D 141.881334, -17.147639 (+/-0.5" J2000):
Epoch 1:
r' =3D 23.6 +/- 0.1
i' =3D 23.6 +/- 0.2
Epoch 2:
r' =3D 23.5 +/- 0.1
i' =3D 23.3 +/- 0.2
These magnitudes are in the AB system, not corrected for Galactic
extinction in the direction of the GRB, and calibrated relative to USNO-B=
1.
We find that source #5 has remained approximately constant in flux over =
a
2 day period. It has not faded and is therefore unlikely to be the
afterglow of GRB 130310A. This source is not detected in the Z, Y, J, or=
H
bands. We also note that we have searched for additional fading sources
(delta_mag > 0.5) in all bands and have found none.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedr=
o
M=E1rtir.
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