GRB 160313A

A. D'Ai (INAF-IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
A. Y. Lien (GSFC/UMBC), A. Maselli (INAF-IASFPA),
L. M. McCauley (PSU), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU) and
T. N. Ukwatta (LANL) report on behalf of the Swift Team:

At 02:37:15 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160313A (trigger=678929).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 183.788, +57.293 which is 
   RA(J2000)  =  12h 15m 09s
   Dec(J2000) = +57d 17' 34"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several peaks
with a total duration of about 40 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~30 sec after the trigger. 

The XRT began observing the field at 02:39:48.3 UT, 152.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 183.7969, 57.2840 which
is equivalent to:
   RA(J2000)  = 12h 15m 11.24s
   Dec(J2000) = +57d 17' 02.3"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 36 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. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

UVOT took a finding chart exposure of 150 seconds with the White
filter  starting 198 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 100% of  the XRT 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 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 0.01. 

Burst Advocate for this burst is A. D'Ai (antonino.dai AT ifc.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.)

A. Moskvitin (SAO RAS, Russia) report on behalf of the larger team.


The field of GRB 160313A (D'Ai et al., GCNC #19171) was observed
with the SAO RAS Zeiss-1000 telescope. The observations started during
the morning twilight, since 10 minutes after the trigger.

In combined image of 4 x 60 seconds in the Rc band we did not detect
any object within the XRT error circle down to the limiting magnitude
R_lim = 18.2. This estimation based on the nearby USNO-B1 stars.

Antonino Cucchiara (GSFC/STScI), Nat Butler (ASU), Alan M. Watson
(UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G.
Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom
(UCB), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos�� A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Neil Gehrels (GSFC),
Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and
Vicki Toy (UMD) report:

We observed the field of GRB 160313A (D'Ai, et al., GCN 19171
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 ) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astron��mico Nacional on
Sierra San Pedro M��rtir from 2016/03 13.14 to 2016/03 13.22 UTC (0.63
to 2.67 hours after the BAT trigger), obtaining a total of 1.42 hours
exposure in the r and i bands and 0.52 hours exposure in the Z,
Y, J, and H bands.


For a source within the Swift-XRT error circle, in comparison with the 
SDSS DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

  r	> 23.49
  i	> 23.21
  Z	> 22.08
  Y	> 21.48
  J	> 20.11
  H	> 20.60

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. Further observations are planned.

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro 
M��rtir.

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

Using 722 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 160313A, 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 = 183.79649, +57.28347 which is equivalent
to:

RA (J2000): 12h 15m 11.16s
Dec (J2000): +57d 17' 00.5"

with an uncertainty of 1.9 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.

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 160313A detected by SWIFT
(trigger 678929) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 122s after the GRB trigger
(20s after the notice). The elevation of the field decreased from
64 degrees above horizon and weather conditions
were good but images are slightly defocused.

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 in the XRT error box published
by Goad et al. (GCNC 19174). Next images are recorded
with diurnal tracking.

t1(s) t2(s)  Rmag_lim  Site
  122   182   15.8      TAROT Calern
  198   228   16.9      TAROT Calern
  239   269   16.8      TAROT Calern
  280   393   18.7      TAROT Calern
  405  1226   18.7      TAROT Calern
1237  3172   19.2      TAROT Calern

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

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

We have analysed 7.1 ks of XRT data for GRB 160313A (D'Ai et al. GCN
Circ. 19171
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 ), from 138 s to 22.9 ks after the  BAT trigger. The data
comprise 39 s in Windowed Timing (WT) mode (the first 7 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 Goad et al.
(GCN Circ. 19174
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 ).

The light curve can be modelled with a power-law decay with a decay
index of alpha=3.23 (+0.18, -0.16).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.9 (+/-0.4). The
best-fitting absorption column is  1.7 (+1.4, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 1.3 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.8 x 10^-11 (4.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.7 (+1.4, -1.1) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 2.3 sigma
Photon index:	     1.9 (+/-0.4)

If the light curve continues to decay with a power-law decay index of
3.23, the count rate at T+24 hours will be 1.1 x 10^-8 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x
10^-19 (5.0 x 10^-19) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00678929.

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

D. Kopac (U. Ljubljana), C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), 
A. Gomboc (U. Nova Gorica), C.G. Mundell (U. Bath), on behalf of a large 
collaboration report:

The 2-m Liverpool Telescope began observing Swift GRB 160313A (D'Ai et 
al., GCN 19171
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 ) on March 13, 02:40:45 UT (3.5 minutes after the burst 
trigger). Inside the XRT error circle (Goad et al., GCN 19174
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 ) we find 
no source down to r'> 21.0 mag in a 6x10s exposure (at 36.5 min, mid 
time), as calibrated against nearby SDSS stars, in agreement with 
previous reports (Moskvitin et al. GCN 19172
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 ; Cucchiara et al. GCN 
19173
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 ; Klotz et al. GCN 19175
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 ).

E. Gorbovskoy, V. Lipunov,  V.Kornilov, D.Kuvshinov, N.Tyurina, 
P.Balanutsa, A.Kuznetsov, V.V.Chazov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik
Kislovodsk Solar Station of the Pulkovo Observatory

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

V.Krushinski, I.Zalozhnih,  A. Popov
Ural Federal University, Kourovka

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

Claudio Mallamaci, Carlos Lopez and Federico Podest
Observatorio Astronomico Felix Aguilar (OAFA)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in Kislovodsk was pointed to the  GRB160313A 21 sec after notice 
time and 129 sec after trigger time at 2016-03-13 02:39:24 UT in two 
polarizations. On our first (30s exposure) and following coadd images 
we haven`t found optical transient  within SWIFT error-box (D'Ai et al GCN 
19171
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 ). The observations took during the morning twilight. We have a 5 
good images before they become overexposed.

The 5-sigma upper limit has been about 16.5 on first single (30s exposure) 
image and 17.2 on coadd (300 s exposure) image.

The message may be cited.

Kugel F., Rinner C. (Observatoire Chante-Perdrix, Dauban),
and Klotz A. (CNRS-OMP-IRAP) report:

F. Kugel imaged the field of GRB 160313A detected by SWIFT
(trigger 678929) with the D=40cm F/D=3 telescope
located at the Observatoire Chante-Perdrix, Dauban,
France (IAU station A77). The CCD camera is
ARTEMIS ATIK-460ex, no optical filter is used.

The observations started 17.4 min after the GRB trigger.

The first image is 60 second exposure.
No optical transcient is detected in the XRT
error box published by Goad et al. (GCNC 19174).
Next images are co-added:

t1(min) t2(min)  Rmag_lim
17.4    18.4     19.5
17.4    42.4     20.0

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

S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), A. D'Ai (INAF-IASFPA),
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-691 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160313A (trigger #678929)
(A. D'Ai et al., GCN Circ. 19171
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 ).  The BAT ground-calculated position is
RA, Dec = 183.821, 57.278 deg which is
  RA(J2000)  =  12h 15m 17.0s
  Dec(J2000) = +57d 16' 40.1"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.

The mask-weighted light curve shows a complex structure with several
overlapping pulses. The structure starts at ~ T-5 s and ends at ~ T+45 s.
T90 (15-350 keV) is 42.6 +- 6.4 sec (estimated error including systematics).

The time-averaged spectrum from T-5.6 to T+44.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.36 +- 0.23.  The fluence in the 15-150 keV band is 5.8 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+24.79 sec in the 15-150 keV band
is 0.4 +- 0.1 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/678929/BA/

L. M. McCauley (PSU) and A. D'Ai (INAF-IASFPA) reports on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160313A
198 s after the BAT trigger (D'Ai et al., GCN Circ. 19171
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 ).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 19174
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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              198         920         418        >20.77
white                 198        5756         664        >21.01
v                     355        6167         451        >19.78
b                     454        5552         254        >20.24
u                     430        6588         260        >19.44
uvw1                  405        6577         451        >19.93
uvm2                 4737        6372         393        >19.17
uvw2                 4328        5962         393        >19.99


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).

E. Mazaeva (IKI),  A. Volnova (IKI),  E. Klunko (ISTP),  I. Korobtsev 
(ISTP),  A. Pozanenko (IKI) report on behalf of larger GRB follow-up 
collaboration:

We observed the field of the GRB 160313A (D'Ai et al., GCN  19171
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 ) with 
AZT-33IK telescope of Sayan observatory (Mondy)  starting on March, 13 
(UT) 16:39:40.  We do not detect any source within enhanced Swift-XRT 
position (Goad et al., GCN 19174
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 ). Preliminary photometry  of  the 
combined image is following

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

2016-03-13  16:39:40  0.60586  R       30*120  23.6

Photometry is based on nearby SDSS-DR9 stars, Lupton transformations into R.

The nearest source to the enhanced XRT position is 5.5 arcsec East, in 
coordinates (J2000) 12:15:11.86 +57:17:00.0 with uncertainty of 0.5 
arcsec in both coordinates. The source magnitude is R=23.3+/-0.2. The 
source is not presented in SDSS-DR9 but barely visible in SDSS r-image.

K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson 
(Curtin), C. Rumsey, D. Titterington, S. Carey, J. Hickish, Y. C. 
Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife 
(Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
160313A (D'Ai et al., GCN 19171
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 ) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2016 Mar 13.15, Mar 13.97, Mar 
16.00, Mar 20.11, and Mar 23.02 (UT) do not reveal any radio source at 
the XRT location (Goad et al., GCN 19174
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 ), with 3sigma upper limits of 
130 uJy, 60 uJy, 100 uJy, 170 uJy, and 70 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.