GRB 140817A

Daniele Malesani (DARK/NBI), Jyri Lehtinen (Univ. Helsinki), and Pall 
Jakobsson (Univ. Iceland), report on behalf of a larger collaboration:

We observed the field of GRB 140817A (Sbarufatti et al., GCN 16695
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 ) with 
the Nordic Optical Telescope (NOT) equipped with the AlFOSC camera. 
Observations were carried out starting on 2014 Aug 20.23 UT (2.94 days 
after the GRB), at high airmass and in twilight, for a total exposure of 
15 min.

No source is detected at the position of the UVOT optical afterglow 
(Marshall & Sbarufatti, GCN 16710
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 ) nor within the XRT error circle 
(Sbarufatti, GCN 16696
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 ; Osborne et al., GCN 16697
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 ) down to a 3-sigma 
limiting magnitude of R = 21 (calibrated against the USNO-B1.0 catalog).

The galaxy MCG +10-12-141 at z ~ 0.018, around 1 arcmin away of the XRT 
position, is well detected in our images (Cummings & Page, GCN 16698
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 ). 
We note that a supernova similar to SN 1998bw would have R ~ 17.5 at z = 
0.018 at a comparable epoch. We thus disfavor the association of GRB 
140817A with the nearby galaxy.

A. Pozanenko (IKI),  N. Tungalag (Research Center of Astronomy and 
Geophysics MAS),  S. Schmalz (AIP), A. Volnova (IKI), I.Molotov (KIAM) 
report on behalf of larger GRB follow-up collaboration:

We observed the  field of GRB 140817A (Sbarufatti et al., GCN 16695
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 ) 
with ORI-40 telescope of Khureltogot observatory.  We started 
observation on Aug. 17 (UT) 14:20:48 and obtained 60 unfiltered images 
of 60 s exposure. Within enhanced XRT error circle  (Osborne et al., GCN 
16697
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 ) we do not detect any new object and in particular the afterglow 
candidate (Marshall et al., GCN 16710
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 ). Details of a photometry of the 
stacked image is following

Date       UT start   t-T0    Filter   Exp.   UL(3 sigma)
                      (mid, days)        (s)

2014-08-17 14:20:48  0.3269   None    60*60   18.2

The photometry is based on USNO-B1.0 star 1481-0233222 assuming 
R=15.43.

F. E. Marshall (NASA/GSFC) and B. Sbarufatti (INAF-OAB/PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140817A
101 s after the BAT trigger (Sbarufatti et al., GCN Circ. 16695
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 ).
A fading source consistent with the UVOT-enhanced XRT position
(Osborne et al. GCN Circ. 16697
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 ) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  08:29:03.21 = 127.26336 (deg.)
  Dec (J2000) =  58:11:24.7  =  58.19020 (deg.)
with an estimated uncertainty of 0.53 arc sec. (radius, 90% confidence).

Preliminary detection and 3-sigma upper limits 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              101         1017          334         20.3 +/- 0.17
white             5426        18414         1794        >21.6
v                  642         1068           58        >18.0
b                  568          762           39        >18.5
u                  313         4899          435        >20.5
w1                 692         1117           39        >19.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.15 in the direction of the burst
(Schlegel et al. 1998).

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

A long-duration GRB 140817A (Swift-BAT trigger 609736:
Sbarufatti et al., GCN 16695
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 ; Cummings et al., GCN 16699
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 ;
Fermi-GBM detection: Roberts & Meegan, GCN 16700
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 )
triggered Konus-Wind at T0=25319.509 s UT (07:01:59.509).

The light curve shows a double-peaked structure from ~T0-0.5 s to ~T0+3.5 s,
the emission in this episode is visible up to ~8 MeV.
The subsequent broad, weak, soft pulse is visible in the instrument's
soft energy channel from ~T0+160 s to ~T0+270 s; it coincides in time with
the bright X-ray flare in the XRT light curve
(http://www.swift.ac.uk/xrt_products/00609736).

As observed by Konus-Wind, the burst had a fluence
of 3.4(-0.3,+0.3)x10^-6 erg/cm2, and a 64-ms peak flux,
measured from T0+2.816 s, of 3.0(-0.3,+0.3)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst (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 = -0.22 (-0.37,+0.40),
the high energy photon index beta = -2.8 (-7.2,+0.4),
the peak energy Ep = 118 (-18,+29) keV,
chi2 = 84/84 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB140817_T25319/

All the quoted errors are at the 95% confidence level.
All the quoted values are preliminary.

P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), V. D'Elia
(ASDC), M. de Pasquale (INAF-IASFPA), A. Maselli  (INAF-IASFPA), D.N.
Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), J.P. Osborne (U.
Leicester) and B. Sbarufatti report on behalf of the Swift-XRT team:

We have analysed 8.9 ks of XRT data for GRB 140817A (Sbarufatti  et al.
GCN Circ. 16695
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 ),  from 79 s to 29.9 ks after the  BAT trigger. The
data comprise 590 s in Windowed Timing (WT) mode (the first 9 s were
taken while Swift was slewing) with the remainder in Photon Counting
(PC) mode. The enhanced XRT position for this burst was given by
Osborne et al. (GCN Circ. 16697
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 ).

The late-time light curve (from T0+4.7 ks) can be modelled with  a
power-law decay with a decay index of alpha=0.86 (+/-0.08).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.625 (+/-0.030). The
best-fitting absorption column is  2.45 (+0.15, -0.14) x 10^21 cm^-2,
in excess of the Galactic value of 8.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.79 (+0.11, -0.10)
and a best-fitting absorption column of 2.3 (+/-0.4) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.0 x 10^-11 (5.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.3 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 8.0 x 10^20 cm^-2
Excess significance: 6.1 sigma
Photon index:	     1.79 (+0.11, -0.10)

If the light curve continues to decay with a power-law decay index of
0.86, the count rate at T+24 hours will be 0.033 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x
10^-12 (1.7 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00609736.

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

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

"At 07:01:58.19 UT on the 17th of August 2014, the Fermi Gamma-Ray
 Burst Monitor triggered and located GRB 140817A (trigger 429951721
/ 140817293), which was also detected by the BAT and XRT on Swift
(Sbarufatti et al., Evans et al. and Cummings et al. 2014, GCNs
16695
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 -99). The GBM on-ground location is consistent with the Swift
position. The angle from the Fermi LAT boresight is 124 degrees.

The GBM light curve consists of two bright peaks with a duration (T90)
of about 16 s (50-300 keV). The time-averaged spectrum from T0-9 s to
T0+16 s is adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.64 +/- 0.19  and the
cutoff energy, parameterised as Epeak, is 130 +/- 11 keV.

The event fluence (10-1000 keV) in this time interval is
(5.03 +/- 0.04)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+5.8 s in the 10-1000 keV band is 10.6 +/- 0.5 ph/s/cm^2.

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

J. R. Cummings, S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
  
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 140817A (trigger #609736)
(Sbarufatti, et al., GCN Circ. 16695
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 ).  The BAT ground-calculated position is
RA, Dec = 127.244, 58.191 deg which is
    RA(J2000)  =  08h 28m 58.5s
    Dec(J2000) = +58d 11' 27.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 75%.
  
The mask-weighted light curve shows multiple sharp peaks from T-20 to T+12 seconds,
then a return to background levels until about T+170 seconds where 2 overlapping
FRED peaks begin, lasting until about T+250 seconds.  T90 (15-350 keV) is
244 +- 13 sec (estimated error including systematics).
  
The time-averaged spectrum from T-21.26 to T+270.27 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.48 +- 0.08.  The fluence in the 15-150 keV band is 4.6 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+2.64 sec in the 15-150 keV band
is 7.2 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/609736/BA/

GRB 140817A Close to nearby galaxy

J. R. Cummings, K. L. Page (U Leicester) on behalf of the Swift science team:

We note the presence of a low-redshift galaxy in DSS, SDSS, 2MASS (SIMBAD) whose
center is 98 arcseconds from the center of the Swift-XRT refined position error
circle (Osborne, GCN Circ. # 16697), MCG+10-12-141 at z ~ 0.018368. The angular
size of the galaxy is about 0.8 arcmin.

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 448 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 140817A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 127.26394, +58.19002 which is equivalent
to:

RA (J2000): 08h 29m 3.35s
Dec (J2000): +58d 11' 24.1"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

B. Sbarufatti (INAF-OAB/PSU) reports on behalf of the Swift-XRT team

Using promptly downlinked data we find a bright, fading X-ray
source with an enhanced position: RA,Dec = 127.2646, 58.1901
(degrees) which is equivalent to:

RA  (J2000.0) = 08 29 03.51
DEC (J2000.0) = +58 11 24.4

with an uncertainty of 2.2 arcsec (radius, 90% containment).
This location is 16.8 arcseconds from the BAT onboard position, inside the BAT
error circle.

B. Sbarufatti (INAF-OAB/PSU), J. R. Cummings (NASA/UMBC),
C. Gronwall (PSU) and D. M. Palmer (LANL) report on behalf of the
Swift Team:

At 07:02:01 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140817A (trigger=609736).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 127.256, +58.189 which is 
   RA(J2000) = 08h 29m 01s
   Dec(J2000) = +58d 11' 21"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multiply-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~16000 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 07:03:36.4 UT, 95.2 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 100 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 5% of
the BAT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
BAT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.15. 

Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)