GRB 140810A

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on
behalf of the GRS-Odyssey GRB team,

S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks, 
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,

J. Goldsten, on behalf of the MESSENGER NS GRB 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, C. Meegan, and V. Pelassa, on behalf of the Fermi
GBM team, report:

GRB 140810A (Moretti et al. GCN 16678
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 , Golenetskii et al. GCN 16679
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 ,
Roberts et al. GCN 16680
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 ) has been observed by Odyssey-HEND, MESSENGER
GRNS, Konus-Wind, INTEGRAL SPI-ACS, and Fermi GBM and LAT, so far.  We
have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:

  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   119.056 (07h 56m 13s) +27.413 (+27d 24' 47")
  Corners:
   119.076 (07h 56m 18s) +28.016 (+28d 00' 58")
   119.014 (07h 56m 04s) +26.723 (+26d 43' 23")
   119.470 (07h 57m 53s) +28.814 (+28d 48' 49")
   118.462 (07h 53m 51s) +25.183 (+25d 10' 57")
  ---------------------------------------------
The error box area is 1450  sq. arcmin., and its maximum/minimum
dimensions are 3.74/0.096 deg. 

This error box is consistent with the Fermi-LAT 90% confidence,
statistical-only error circle (GCN 16678
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 ), and constrains it slightly.
A map has been posted at ssl.berkeley.edu/ipn3/140810A.  This
localization may be improved.

Oliver Roberts (UCD) and Matthew Stanbro (UAH)
report on behalf of the Fermi GBM Team:

"At 18:46:10.09  UT on the 10th of August 2014, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 140810A
(trigger 429389173 / 140810782), which was also detected by the LAT
(Bissaldi et al. 2014, GCN 16678
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 ). The trigger resulted in an
Autonomous Repoint Request (ARR) that was accepted. The GBM
on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight is 122 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 82 s (50-300 keV). The time-averaged spectrum from
T0-3.58 s to T0+107.01 s is well fit by a power law function with an
exponential high-energy cutoff. The power law index is -1.01 +/- 0.01
and the cutoff energy, parameterised as Epeak, is 302 +/- 7 keV.

The event fluence (10-1000 keV) in this time interval is
(110.42 +/- 0.07)E-06 erg/cm^2. The 1.024-sec peak photon flux
measured from T0+6.6 s in the 10-1000 keV band, is
35.98+/-0.65 ph/s/cm^2.

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

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 140810A (Fermi-LAT detection: Moretti et al., GCN 16678
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 )
triggered Konus-Wind at T0=67571.433 s UT (18:46:11.433).

The light curve shows a multi-peaked structure with a total duration of ~100 s.
The emission is seen up to 10 MeV.

As observed by Konus-Wind, the burst had a fluence
of 1.5(-0.1,+0.1)x10^-4 erg/cm2, and a 64-ms peak flux,
measured from T0+23.104 s, of 1.3(-0.1,+0.1)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+93.696 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 = -1.05 (-0.06,+0.05),
the high energy photon index beta = -2.35 (-0.16,+0.12),
the peak energy Ep = 239 (-26,+25) keV,
chi2 = 105/97 dof.

The spectrum near the peak count rate (measured from T0+16.640 to T0+29.959 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 = -0.86 (-0.10,+0.10),
the high energy photon index beta = -2.44 (-0.35,+0.17),
the peak energy Ep = 416 (-47,+63) keV,
chi2 = 87/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB140810_T67571/

All the quoted errors are at the 90% sigma confidence level.
All the quoted values are preliminary.

Elena Moretti (MPI Munich), Makoto Arimoto (Tokyo Tech),
Elisabetta Bissaldi (University & INFN Trieste), Sylvain Guiriec
(GSFC/CRESST/UMD) and Giacomo Vianello (Stanford University)
report on behalf of the Fermi-LAT team:


At UT 18:46:10.09 on August 10th, 2014, Fermi-LAT detected
high-energy emission from GRB 140810A, which was also
detected by Fermi-GBM (trigger 140810782/429389173).

The best LAT on-ground location is found to be

(RA, Dec) = 119.04, 27.55 (deg, J2000)

with an approximate error radius of 0.12 deg (90% containment,
statistical error only). The error circle is slightly asymmetric,
the Test Statistic localisation map (with 68% and 90% contours)
can be found here: http://fermigrb.stanford.edu/140810782.jpg.
The location could be updated later as more data become available
(at the moment of writing we can analyse up to 2000 s after the trigger).
The burst was 123 deg from the LAT boresight at the time of
the trigger and the high fluence detected by GBM caused the
GBM flight software to initiate a Fermi autonomous re-point
that placed the source in the LAT FoV about 330 s after the trigger.

The data from the Fermi-LAT show a significant increase
in the event rate that is spatially correlated
with the GBM emission with high significance.
More than 20 photons above 100 MeV and 3 photons
above 1 GeV are observed.
The highest-energy photon is a 16  GeV event,
which is observed about 1500 s after the GBM trigger.

A Swift ToO has been requested for this burst, but the burst can not
be observed due to Sun constrains.

The Fermi-LAT point of contact for this burst
is Elena Moretti (moretti@mpp.mpg.de)


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.