GRB 141031A

B.P. Gompertz (U Leicester), J. R. Cummings (NASA/UMBC),
K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of
the Swift Team:

At 07:18:26 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 141031A (trigger=617110).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 128.599, -59.138 which is 
   RA(J2000) = 08h 34m 24s
   Dec(J2000) = -59d 08' 15"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed one peak with a 
duration of about 20 sec.  The peak count rate was ~1437 counts/sec 
(15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 07:20:05.5 UT, 98.9 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 128.60808, -59.16815 which is
equivalent to:
   RA(J2000)  = 08h 34m 25.94s
   Dec(J2000) = -59d 10' 05.3"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 109 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.17 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 2.4
(+2.45/-2.14) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 102 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 none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT 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 0.17. 

Burst Advocate for this burst is B.P. Gompertz (bpg6 AT le.ac.uk). 
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.)

M. Tanga, C. Delvaux (both MPE Garching), D. A. Kann (TLS Tautenburg), P.
Schady and J. Greiner (both MPE Garching) report on behalf of the GROND
team:

We observed the field of GRB 141031A (Swift trigger 617110; Gompertz et
al., GCN #16995
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 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at the ESO La
Silla Observatory (Chile).

Observations started at 07:46 UT on 31 October 2014, 0.45 hrs after the
GRB trigger. They were performed at an average seeing of 1.3" and at an
average airmass of 1.33.

We found one single point source at the NW edge of the 2.1" Swift-XRT
error circle reported by Gompertz et al. (GCN #16995
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 ) at

RA (J2000.0) = 08h 34m 25.75s

DEC (J2000.0) = -59d 10' 05.0"

with an uncertainty of 0.3" in each coordinate.

Based on the first 8.8 min of total exposures in g'r'i'z' and 8.0 min in
JHK, we estimate preliminary magnitudes (all in AB system) of

g' = 22.7 +/- 0.1 mag,
r' = 21.7 +/- 0.1 mag,
i' = 21.5 +/- 0.1 mag,
z' = 21.5 +/- 0.1 mag,
J > 20.9 mag,
H > 20.3 mag, and
K > 18.7 mag.

At the moment we cannot confirm if the source is fading.

Given magnitudes are calibrated against GROND zeropoints as well as 2MASS
field stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.17 mag in the
direction of the burst (Schlegel et al. 1998).

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

Using 1789 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 141031A, 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 = 128.60838, -59.16828 which is equivalent
to:

RA (J2000): 08h 34m 26.01s
Dec (J2000): -59d 10' 05.8"

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.

O.J. Roberts (UCD) reports on behalf of the Fermi GBM Team:

"At 07:18:21.67 UT on the 31st of October 2014, the Fermi
Gamma-Ray Burst Monitor triggered and located GRB 141031A
(trigger 436432704 / 141031304), which was also detected by
Swift (Gompertz et al. 2014, GCN 16995
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 ). The GBM on-ground
location, using the Fermi GBM trigger data, is consistent with
the Swift location.

The angle from the Fermi LAT boresight is about 34 degrees.

The GBM light curve consists of a single peak with a duration
(T90) of about 19.4 s (50-300 keV). The time-averaged spectrum
from T0-6.1 s to T0+13.3 s is well fit by a power law function
with an exponential high-energy cutoff.  The power law index is
-1.09 +/- 0.06  and the cutoff energy, parameterized as Epeak,
is 410 +/- 66 keV.

A Band function fits the spectrum equally well with
Epeak = 221 (+/-57) keV, alpha = -0.92 +/- 0.12 , and
beta = -1.76 (+/-0.09).

The event fluence (10-1000 keV) in this time interval is
(5.7 +/- 0.2)E-06  erg/cm^2. The 1-sec peak photon flux
measured starting from T0+3.8 s in the 10-1000 keV band
is 2.7 +/- 0.2 ph/s/cm^2.

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

________________________________

D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA/CSIC and DARK/NBI), S. D. 
Vergani (CNRS/GEPI), A. J. Levan (Univ. Warwick), J. P. U. Fynbo 
(DARK/NBI), N. R. Tanvir (Univ. Leicester), B. Milvang-Jensen 
(DARK/NBI), D. Malesani (DARK/NBI), K. Wiersema (Univ. Leicester), 
report on behalf of a larger collaboration:


We observed the field of GRB 141031A (Gompertz et al., GCN 16995
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 ) using 
the VLT X-shooter spectrograph, using the robotic rapid response mode (RRM).

In a 15-s acquisition image, taken at 7:41:19 UT (22.8 min after the 
GRB1), we identify three objects consistent with, or in the close 
vicinity of, the currently available XRT error circle (1.4" error 
radius; Evans et al., GCN 16997
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  and http://www.swift.ac.uk/xrt_positions/).

Their coordinates are (all J2000):

A)
RA = 08:34:26.11
Dec = -59:10:04.2

B)
RA = 08:34:25.73
Dec = -59:10:04.8

C)
RA = 08:34:26.05
Dec = -59:10:04.9

Sources A and C are partially blended. Source B is the one detected by 
GROND (GCN 16996
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 ), looks extended in our data (under 0.6" seeing), and 
is now formally outside the latest XRT position (2.7"+-1.4" away). The 
limiting magnitude of the image is R ~ 21.7. A finding chart is 
available at http://www.astro.ku.dk/~malesani/GRB/141031A/finder_XS.jpg

A later image (30 s exposure) was taken 104.5 min after the GRB. Image 
subtraction reveals no obvious variation of any of the sources, despite 
the significant time difference between the two epochs (factor of 4.5 in 
time since GRB).

A spectrum was secured of source A, covering the wavelength range 
3000-25,000 AA. Several features are observed in absorption, including 
the Balmer series from Halpha to H15, and Ca H and K, at z = 0.0013. 
Such redshift is consistent with the Milky Way or the Local Group, 
though the corresponding velocity (390 km/s) is substantial for an 
origin in the MW disk.

Our slit did not cover, unfortunately, objects B and C. Further analysis 
is in progress, and we invite further monitoring of these object to 
single out variability.

We acknowldge excellent support from the observing staff in Paranal, in 
particular Juan Carlos Munoz-Mateos, Francisco Caceres, Rodrigo Romero, 
and Steffen Mieske.

A. Trotter, J. Haislip, D. Reichart, A. Aji, R. Beauchemin, T. Berger, 
A. Dow, A. Foster, N. Frank, M. Hinckle, K. Ivarsen, A. LaCluyze, M. 
Maples, J. Moore, M. Nysewander, C. Salemi, L. Zbinden, and J. A. Crain 
report:

Skynet observed the Swift BAT/XRT localization of GRB 141031A (Gompertz 
et al., GCN 16995
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 , Swift trigger=617110) with one 24" telescope (PROMPT 
8; I band) and three 16" telescopes (PROMPT 3,4,5; B,R,I bands) of the 
PROMPT array at CTIO, Chile.
Starting at 2014-10-31 07:19:46 UT and continuing until 08:53 UT 
(t=79s-94m post-trigger), Skynet took a total of 196 exposures ranging 
from 10s-160s each. We stacked subsets of these images to maximize the 
S/N ratio, and detected no optical source in any band at the OT position 
reported by GROND (Tanga et al., GCN 16996
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 ).  Our 3-sigma limiting 
magnitudes are:

==================================
tmid  scope   expos  fil  limit
==================================
52m  PROMPT3 26x160s  B   >20.9
54m  PROMPT4 24x160s  R   >21.6
53m  PROMPT5 27x160s  I   >20.9
48m  PROMPT8 45x80s   I   >20.9
==================================

Limiting magnitudes are in the Vega System, calibrated to 6 APASS stars 
in the field.  Magnitudes have not been corrected for line-of-sight 
Milky Way dust extinction, with expected E(B-V)=0.15 (Schlafly & 
Finkbeiner 2011).

No further Skynet observations are scheduled.

M. de Pasquale (INAF-IASFPA), J.A. Kennea (PSU), V. Mangano (PSU), M.C.
Stroh (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.
Maselli  (INAF-IASFPA), A. Melandri (INAF-OAB) and B.P. Gompertz report
on behalf of the Swift-XRT team:

We have analysed 8.0 ks of XRT data for GRB 141031A (Gompertz  et al.
GCN Circ. 16995
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 ),  from 102 s to 24.0 ks after the  BAT trigger. The
data comprise 847 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN Circ. 16997
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 ).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=1.06 (+/-0.05).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.43 (+0.12, -0.11). The
best-fitting absorption column is  2.44 (+0.64, -0.27) x 10^21 cm^-2,
consistent with the Galactic value of 2.2 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 5.2 x 10^-11 (6.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.44 (+0.64, -0.27) x 10^21 cm^-2
Galactic foreground: 2.2 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.43 (+0.12, -0.11)

If the light curve continues to decay with a power-law decay index of
1.06, the count rate at T+24 hours will be 4.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.1 x
10^-13 (2.4 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00617110.

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

S. R. Oates (IAA-CSIC/UCL-MSSL) and B. P. Gompertz (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 141031A
102 s after the BAT trigger (Gompertz et al., GCN Circ. 16995
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 ).
No optical afterglow consistent with the possible optical position
(Tanga et al. GCN Circ. 16996
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 ) or enhanced XRT position 
(Evans et al. GCN Circ. 16997
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 ) is detected in the initial UVOT exposures.
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_FC           102          252          147         >20.9
u_FC               315          565          246         >19.9
white              102        18038          967         >21.8
v                  646        13448          759         >20.0
b                  571        17791         1414         >21.4
u                  315        23978         1180         >20.7
w1                 696        23537         1396         >21.0
m2                 670         6964          529         >20.2
w2                 621        12030         1238         >21.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.17 in the direction of the burst
(Schlegel et al. 1998).

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),  W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings, 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), J. Tueller (GSFC)
(i.e. the Swift-BAT team):
  
Using the data set from T-250 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 141031A (trigger #617110)
(Gompertz, et al., GCN Circ. 16995
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 ).  The BAT ground-calculated position is
RA, Dec = 128.632, -59.160 deg which is
    RA(J2000)  =  08h 34m 31.6s
    Dec(J2000) = -59d 09' 36.8"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.
  
The mask-weighted light curve shows three widely separated peaks.  The first
is a single symmetric peak from about T-20 to T+20 seconds, the second is
another symmetric peak ~20 sec long at about T+800, and the third is two
overlapping peaks from about T+850 to T+920 seconds.  T90 (15-350 keV) is
about 920 +- 10 sec (estimated error including systematics).
  
The time-averaged spectrum from T-22 to T+20 sec is best fit by a simple
power-law model with a power law index of 1.21 +- 0.13.  The time-averaged
spectrum from T+770 to T+920 sec is also best fit by a simple power-law model
with a power law index of 1.75 +- 0.18.  The total fluence for both intervals
in the 15-150 keV band is 2.9 +- 0.5 x 10^-06 erg/cm2.  The 1-sec peak photon
flux measured from T+5.08 sec in the 15-150 keV band is 0.5 +- 0.2 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/617110/BA/

Klotz A., Turpin D. (IRAP-CNRS-OMP),
Boer M., Gendre B., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA),
Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 141031A detected by SWIFT
(trigger 617110) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 45s after the GRB trigger
(15s after the notice). The elevation of the field increased from
45 degrees above horizon and weather conditions
were excellent.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+45s to t0+105s : Rlim = 14.8

Following images are recorded in tracking mode.
We used late images to substract non variable stars
in the XRT error box.

The second image is 30.0s exposure in tracking mode:
t0+119s to t0+149s : Rlim = 17.5

Later images (until 1800s after the trigger) do not
show any optical afterglow at Rlim = 17.5

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.