GRB 131029A

J. L. Racusin (NASA/GSFC), G. Vianello (Stanford), Elisabetta Bissaldi (University & INFN Trieste), Rachele Desiante 
(University of Udine and INFN Trieste), Francesco Longo (University and INFN Trieste), report on behalf of 
the Fermi-LAT team:

Starting around 23:20:48.58 on October 29, 2013 Fermi LAT detected high energy emission from GRB 131029A, 
which was also detected by Fermi-GBM (trigger 404781651/131029973).

The best LAT on-ground location is found to be RA, DEC 200.785, 48.298 (J2000) with an error radius of 0.26 deg 
(68% containment, statistical error only), this was 60 deg from the LAT boresight at the time of the trigger (i.e., close 
to the limit of the LAT field of view). This position is ~6 deg away from the best available GBM position, well within 
the error radius if we include a typical systematic error of 3 deg.  The burst position was observed by the LAT from 
the trigger until ~T0+800 s.

The data from the Fermi LAT show a significant increase in the event rate within 10 degree of the GBM location after 
the GBM trigger that is spatially and temporally correlated with the GBM emission with high significance. More than 
19 photons above 100 MeV and more than 3 photons above 1 GeV are observed within 800 seconds. The highest 
energy photon is a 1.3 GeV event which is observed 70 seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi LAT point of contact for this burst is Judith Racusin (judith.racusin@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.

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
Fermi/LAT GRB 131029A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00020

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; and 2009, MNRAS, 397, 1177).

This circular is an official product of the Swift-XRT team.

A. von Kienlin (MPE) and P. Jenke  (UAH)
report on behalf of the Fermi GBM Team:

"At 23:20:48.58 UT on 29 October 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 131029A (trigger 404781651 / 131029973), 
which was also detected by Fermi/LAT (Racusin et al. 2013, GCN 15399
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 ). 
The GBM on-ground location is consistent with the LAT position. 
At the time of triggering the angle from the Fermi LAT boresight was
59 degrees. 

The GBM light curve consists of a double peaked pulse 
with a duration (T90) of about 105 s (50-300 keV).
The time-averaged spectrum from T0-3.072 s to T0+100.353 s is
best fit by a Band function with Epeak = 230 +/- 20 keV,
alpha = -1.02 +/- 0.04, and beta = -2.1 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(3.0 +/- 0.1)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+4.2 s in the 10-1000 keV band
is 4.6 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), J.L. Racusin
(NASA/GSFC) report on behalf of the Swift-XRT team

The Swift-XRT has observed the vicinity of GRB 131029A (Racusin et al.,
GCN 15399
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 ); gathering 600-900 s on each of 7 tiled pointings (see Evans,
GCN Circ. 15400
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 ), covering the entire LAT 90% error circle.

No credible X-ray afterglow has been found: we find three sub-threshold
(i.e. low significance) detections, 2 of which are near to catalogued
X-ray sources and the other is near to an object in SIMBAD.

The 3-sigma XRT upper limit for the field is approximately 0.01 ct/sec.

This circular is an official product of the Swift-XRT team.

D. Xu (DARK/NBI), G.-J. Feng, H.-B. Niu, A. Esamdin, L. Ma (XAO) report:

We observed the field of the LAT error circle of GRB 131029A (Racusin
et al., GCN 15399
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 ) using the 1m telescope located at Mt. Nanshan,
Xinjiang, China, equipped with a 1.2x1.2 deg^2 CCD camera. Three
R-band frames with exposures of 180s, 240s, and 300s were obtained at
a mean time of 13.656 hr after the Fermi/LAT trigger.

At the reported three sub-threshold XRT positions (Evans, GCN 15400
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 ),
no optical transient is detected down to a limiting magnitude of
R=19.5 mag, calibrated with nearby SDSS field.

H. Ueno, M. Tashiro, Y. Terada, T. Yasuda, Y. Ishida, S. Sugimoto
(Saitama U.), M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui,
Y. Fukazawa (Hiroshima U.), M. Yamauchi, N. Ohmori, M. Akiyama,
R. Kinoshita (Univ. of Miyazaki), K. Yamaoka (Nagoya U.), S. Sugita
(Ehime U.), Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA),
W. Iwakiri(RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa,
K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:

The long GRB 131029A (Fermi-LAT detection: A. von Kienlin, et al., GCN
15401
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 ) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers 
an energy range of 50 keV - 5 MeV at UT 23:20:48.884 (=T0).

The observed light curve shows a two-peaked structure starting at
T0-5.0 s, ending at T0+110 s with a duration (T90) of about 84 seconds.
The fluence in 100 - 1000 keV was 1.51 (-0.36, +0.24) *10^-5 erg/cm^2.
The 1-s peak flux measured from T0+4.0 s was
1.55 (-0.92, +1.3) photons/cm^2/s in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0-2 s to T0+110 s is well fitted by a single power-law with a photon
index of 1.87 (-0.17, +0.17) (chi2/d.o.f = 12.4/12).

Due to the brightness of this burst, a 3% systematic error was added
for low energy channels.
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/trig/grb_table.html