GRB 150710B

J. R. Cummings (CPI), D. M. Palmer (LANL), V. Pal'shin(Ioffe),
and D. Svinkin (Ioffe)

At 08:05:35, the bright GRB 150710B was observed by Swift/BAT during a
preplanned Swiftslew.  It was also seen by KONUS/WIND, and the KW team
notified the BAT team of the event.  In a mosaic of BAT images from photon-
eventdata recorded during the slew, a bright source was found at
RA, Dec 83.195, -46.963,which is:

RA (J2000)05h 32m 46.9s
Dec (J2000) -46d 57' 47"

with an estimated uncertainty of 2 arcmin 90% containment.

The burst had an estimated T90 of about 16 seconds.  There were multiple
bright peaks and an exponential decay.

A Swift TOO has been requested in order to locate the afterglow.

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

Swift has initiated a ToO observation of the Swift/BAT GRB 150710B. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020542

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. 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; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

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

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
  
Using the data set from T-47 to T+50 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150710B.  (Cummings, et al., GCN Circ.
18009
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 ).  The refined BAT position is RA, Dec = 83.191, -46.960 deg, which is
    RA(J2000)  =  05h 32m 45.8s
    Dec(J2000) = -46d 57' 34"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
  
The mask-weighted light curve shows 6 overlapping but well-defined peaks
followed by an exponential decay to background.  T90 (15-350 keV) is
15 +- 1 sec (estimated error including systematics).
  
The time-averaged spectrum from T+0 to T+15 sec is best fit by a model of a
power law with an exponential cutoff.  The photon index of the time-averaged
spectrum is 0.99 +- 0.09.  Epeak was 166 +- 28 keV.  Using this model, the
fluence in the 15-150 keV band was (3.5 +- 0.1) x 10^-6 ergs/cm^2.  A simple
power-law fit has a photon index of 1.34 +- 0.02.

The 1-sec peak photon flux measured from T+3.5 sec in the 15-150 keV band
was 8.3 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

A Swift TOO is being executed (Evans, GCN #18010
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 ).

Because this was a ground-detected burst, the usual automated BAT data
products are not available.

A. Melandri (INAF-OAB), P. Kuin (MSSL-UCL), V. D'Elia (ASDC), A. D'ai
(INAF-IASFPA), L.M. McCauley (PSU), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester),
A.P. Beardmore (U. Leicester), A. Maselli (INAF-IASFPA) and P.A. Evans
(U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 150710B (Cummings et al. GCN Circ. 18009
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 ),
collecting 2.8 ks of Photon Counting (PC) mode data between T0+115.2 ks
and T0+121.6 ks. 

An uncatalogued X-ray source has been detected close to the refined
Swift/BAT error region (Cummings et al. GCN Circ. 18013
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 ), it is below
the RASS limit and shows no definitive signs of fading. Therefore, at
the present time we cannot confirm this as the afterglow. Details of
this source are given below:

  RA (J2000.0):  83.2176  =  05:32:52.23
  Dec (J2000.0): -46.9423  =  -46:56:32.4
  Error: 4.7 arcsec (radius, 90% conf.)
  Count-rate: 0.0141 [+0.0031, -0.0027] ct s^-1

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020542.

Simultaneous with the Swift-XRT, the Swift-UVOT observed the field
of GRB 150710B. Preliminary 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373)
for the first finding chart (FC) exposure and subsequent exposures are:


Filter	       T_start(s)   T_stop(s)	   Exp(s)	Mag

white	       115375	    120586	   662	       >21.1
v	       115594	    121561	   957	       >19.5
u	       115157	    120072	   915	       >20.5

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.04 in the direction of
the burst (Schlegel et al. 1998).

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

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 150710B (Swift-BAT ground detection:
Cummings et al., GCN 18009
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 )
triggered Konus-Wind at T0=29133.922 s UT (08:05:33.922).

The KW light curve shows a multi-peaked emission complex with
a total duration of ~8.5 s.
The emission is visible up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150710_T29133/

As observed by Konus-Wind, the burst had a fluence
of 1.1(-0.2,+0.2)x10^-5 erg/cm2, and a 64-ms peak flux,
measured from T0+4.032 s, of 6.8(-1.3,+1.2)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged 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 = -0.81 (-0.23,+0.30),
the high energy photon index beta = -2.27 (-0.33,+0.18),
the peak energy Ep = 154 (-30,+37) keV,
chi2 = 75/97 dof.

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

A. Melandri, P. D'Avanzo, M.G. Bernardini (INAF-OAB), K.L. Page, P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has conducted further observations of the field of the Swift/BAT-detected burst GRB 150710B (Cummings et al. GCN Circ. 18009
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 ). The observations now extend from T0+115 ks to T0+259 ks.

The source reported by Melandri et al. (GCN Circ. 18018
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 ) has significantly faded between two epochs, down to a level of (7 +/- 2)e-3 cts/s, and is therefore the GRB afterglow.

The results of the full analysis of the XRT observations are available at http://www.swift.ac.uk/ToO_GRBs/00020542.

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