GRB 160801A

K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson 
(Curtin), T. Cantwell (Manchester), 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 
160801A (D'Elia et al., GCN 19744
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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 Aug 02.75, Aug 04.75, and 
Aug 08.73 (UT) do not reveal any radio source at the XRT location (Goad 
et al., GCN 19746
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 ), with 3sigma upper limits of 147 uJy, 123 uJy, and 
126 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/.

E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva 
(Fesenkov Astrophysical Institute),  A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of GRB 160801A  (D'Elia et al., GCN 19744
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  ) with 
Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory. We 
obtained several images in R filter starting on August 01 (UT) 15:10:55. We 
do not  detect any optical source within enhanced XRT error position (Goad 
et al., GCN 19746
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 ). Preliminary photometry of a combined image is following

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

2016-08-01 15:10:55  0.28422  R   60*120 n/d  n/d  22.4

Photometry is based on nearby SDSS DR9 stars
SDSS-DR9_id                   R(Lupton)
J141100.70+132838.3    17.993
J141057.03+132833.7    17.684
J141054.86+132751.0    18.338
J141055.05+132937.2    18.545
J141059.52+133105.4    19.518
J141102.35+133019.9    18.384
J141102.64+133004.5    18.354

Our preliminary  photometry of the SDSS object (Cano et al.,  GCN 19753
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 ) 
which is also mentioned by Moskvitin et al. (GCN 19755
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 )  is R=21.1+/-0.1 and 
based on the same nearby SDSS stars.

A finding chart can be found  in 
http://grb.rssi.ru/GRB160801A/GRB160801A_TSHAO_160801_2.png

B. G. Balzer (PSU) and V. D'Elia (ASDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160801A
90 s after the BAT trigger (D'Elia et al., GCN Circ. 19744
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 ).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 19746
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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 the subsequent summed exposures:

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

white_FC            90          240          147         >20.50
u_FC               302          552          245         >19.91
white              581         1896          283         >20.94
v                  631         1945          155         >18.91
b                  557         1871          136         >19.90
u                  704         1846          116         >19.48
w1                1455         1474           19         >17.77

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).

A. Moskvitin (SAO RAS) and I. Soloviev  (Saint-Petersburg Univ.),
report on behalf of the larger GRB follow-up team.

We observed the field of GRB 160801A (D'Elia et al., GCNC#19744)
with Zeiss-1000 - the 1-meter telescope of Special Astrophysical
Observatory of Russian Academy of Sciences on August 1, 2016,
(18:14:58--20:09:29 UT), T_mid - T0 = 9.73 hours. We have obtained
18 x 300 sec. images in the Rc band under good weather conditions.
Within the XRT error circle (Goad et al., GCNC#19746)
we did not detect any new objects down to the limiting magnitude
R_lim = 23.2.

When inspecting SDSS images we found a faint stellar-like source
J141103.21+132921.4 located near the enhanced XRT error circle.
The recalculated magnitude of the object from SDSS images
(Epoch = 2003.41) should be R = 20.94 +/- 0.05 (based on the
Lupton 2005 equations).

In our stacked frame at the edge of the XRT error circle
(the offset 2".2) we detected the same source with a brightness of
R = 20.9 +/- 0.1. Therefore, we can not detect significant differences
between two epochs. This result is in agreement with info reported
by Cano et al. (GCNC#19753). Our preliminary photometry is based
on the nearby SDSS stars, which magnitudes are converted to the
Johnson-Cousins system with the same Lupton 2005 equations.

The finding chart based on Zeiss-1000 observations can be found at
ftp://ftp.sao.ru/pub/grb/GRB160801A/GRB160801A_z1000.jpg

We are grateful to technical staff of SAO RAS for assistance in
observations.

<ftp://ftp.sao.ru/pub/grb/GRB160801A/GRB160801A_z1000.jpg>

Z. Cano (Univ. Iceland), D. Malesani (DARK/NBI and DTU space), J.-K.
Krogager, P. Noterdaeme (IAP) & A. Djupvik (NOT) report on behalf of a
larger collaboration:

We observed the field of GRB 160801A (D'Elia et al.; GCN Circ. 19744
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 ) with
the 2.5-m Nordic Optical Telescope equipped with ALFOSC, starting at 21:05
UT on 01 August 2016.  We obtained 14 minutes in the z-band and 10 minutes
in the r-band.  In our co-added images we do not detect any new source(s)
within the enhanced XRT error circle (Goad et al.; GCN Circ. 19746
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 ) to the
following limits:

Filter    t-t0 (d)     magnitude limit (AB)
-------------------------------------------
  r       0.50               >24.4
  z       0.49               >23.1

These upper limits are for an isolated point source in the GRB field, they
are calibrated against the SDSS catalogue, and they have not been corrected
for foreground extinction.

We note the presence of an SDSS object (RA = 14:11:03.21, Dec =+13:29:21.5)
just outside the refined XRT error circle. This object is pointlike in our
images (0.8" seeing) and its magnitude did not vary within the errors
compared to the SDSS archival values. We consider it is unlikely that this
object is associated with GRB 160801A.

A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU),
T.G.R. Roegiers (PSU), L.M. McCauley (PSU), B. Mingo (U. Leicester),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and V. D'Elia
report on behalf of the Swift-XRT team:

We have analysed 6.5 ks of XRT data for GRB 160801A (D'Elia et al. GCN
Circ. 19744
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 ), from 96 s to 19.2 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Goad et al. (GCN Circ. 19746
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 ).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.94 (+0.13, -0.11).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.1 (+0.6, -0.5). The
best-fitting absorption column is  6.0 (+3.9, -2.8) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 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 4.0 x 10^-11 (7.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     6.0 (+3.9, -2.8) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 3.5 sigma
Photon index:	     2.1 (+0.6, -0.5)

If the light curve continues to decay with a power-law decay index of
0.94, the count rate at T+24 hours will be 5.8 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.3 x
10^-14 (4.2 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00706871.

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

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), V. D'Elia (ASDC),
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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160801A (trigger #706871)
(D'Elia, et al., GCN Circ. 19744
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 ).  The BAT ground-calculated position is
RA, Dec = 212.763, 13.485 deg which is
    RA(J2000)  =  14h 11m 03.2s
    Dec(J2000) = +13d 29' 06.5"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 73%.

The mask-weighted light curve shows a single peak with ~3 second duration,
peaking at T+0. T90 (15-350 keV) is 2.85 +- 0.41 sec (estimated error including
systematics).

The time-averaged spectrum from T-1.34 to T+1.83 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.85 +- 0.22.  The fluence in the 15-150 keV band is 1.7 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.02 sec in the 15-150 keV band
is 1.2 +- 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/706871/BA/

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

Using 1870 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 160801A, 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 = 212.76274, +13.48921 which is equivalent
to:

RA (J2000): 14h 11m 3.06s
Dec (J2000): +13d 29' 21.1"

with an uncertainty of 2.0 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.

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of MITSuME and OISTER collaboration:

We observed the field of GRB 160801A (D'Elia et al., GCNC 19744)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on 2016-08-01 11:06:56 UT (~1.6 h after
the burst). We did not find any new point source within the XRT
circle (D'Elia et al., GCNC 19744) in all the three bands.

Three sigma upper limits of the OT are listed below.
We used SDSS-DR8 catalog for flux calibration.

#T0+[day]  MID-UT    T-EXP[sec]   g'    Rc     Ic
-----------------------------------------------------
0.10264    11:56:18    2580.0   >19.1  >19.2  >18.6
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]

V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), P.A. Evans (U Leicester),
H. A. Krimm (CRESST/GSFC/USRA) and A. Y. Lien (GSFC/UMBC) report on
behalf of the Swift Team:

At 09:28:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160801A (trigger=706871).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 212.763, +13.499 which is 
   RA(J2000) = 14h 11m 03s
   Dec(J2000) = +13d 29' 58"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 7 sec.  The peak count rate
was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 09:29:57.4 UT, 87.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 212.7629, 13.4895 which
is equivalent to:
   RA(J2000)  = 14h 11m 03.10s
   Dec(J2000) = +13d 29' 22.3"
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This
location is 34 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.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.59
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 90 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
0.02. 

Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.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.)