GRB 111016A

V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
N. Gehrels (NASA/GSFC), C. Guidorzi (U Ferrara), J. A. Kennea (PSU),
D. M. Palmer (LANL), P. Romano (INAF-IASFPA), C. J. Saxton (UCL-MSSL),
M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and
G. Tagliaferri (INAF-OAB) report on behalf of the Swift Team:

At 18:37:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 111016A (trigger=505646).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 153.806, +27.476 which is 
   RA(J2000)  =  10h 15m 13s
   Dec(J2000) = +27d 28' 32"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows at least 7 well separated
peaks with a total duration of at least 230 sec.  The peak count rate
was ~1600 counts/sec (15-350 keV), at ~0 sec after the trigger, and another
equally bright peak at T+160 sec.  And there is a possible peak at T+600 sec. 

The XRT began observing the field at 18:40:03.2 UT, 180 seconds
after the BAT trigger. A bright source was present in the field, 
at the following location RA,Dec(J2000) = 153.8334, 27.4634, which 
is equivalent to:
   RA(J2000)  =  10h 15m 20.0s
   Dec(J2000) = +27d 27' 48.3"
with an estimated error of 5 arc-seconds radius (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White 
filter  starting 187 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 0.04. 

Burst Advocate for this burst is V. Mangano (vanessa 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.)

J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), G.
Cusumano (INAF-IASF PA), M. Perri (ASDC) and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 111016A at 18:40:03.2 UT,
178.7 seconds after the BAT trigger. XRT found a bright, uncatalogued
X-ray source located at RA, Dec 153.8334, +27.4634 which is equivalent
to:
   RA(J2000)  = 10h 15m 20.01s
   Dec(J2000) = +27d 27' 48.2"
with an uncertainty of 6.0 arcseconds (radius, 90% containment). This
location is 98 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.

The initial flux in the 2.5 s image was 0.00e+00 erg cm^-2 s^-1 (0.2-10
keV).

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

Using 5089 s of XRT Photon Counting mode data and 11 UVOT
images for GRB 111016A, 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 = 153.83400, +27.46235 which is equivalent
to:

RA (J2000): 10h 15m 20.16s
Dec (J2000): +27d 27' 44.5"

with an uncertainty of 1.5 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.

V. Mangano (INAF-IASFPA) reports on behalf of the Swift-XRT team:

We have analysed 10 ks of XRT data for GRB 111016A (Mangano  et al. GCN
Circ. 12439
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 ), from 185 s to 23.8 ks after the  BAT trigger. The data
comprise 693 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 12441).

The late-time light curve (from T0+4.1 ks) can be modelled with an
initial power-law decay with an index of alpha=3.62 (+0.24, -0.98),
followed by a break at T+5533 s to an alpha of 1.06 (+0.15, -0.23).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.800 (+/-0.024). The
best-fitting absorption column is  1.85 (+/-0.07) x 10^21 cm^-2, in
excess of the Galactic value of 2.5 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 2.23 (+0.09, -0.14)
and a best-fitting absorption column of 7.3 (+2.2, -3.3) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.2 x 10^-11 (4.1 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     7.3 (+2.2, -3.3) x 10^20 cm^-2
Galactic foreground: 2.5 x 10^20 cm^-2
Excess significance: 3.6 sigma
Photon index:	     2.23 (+0.09, -0.14)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00505646.

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

R. Usui, K. Tokoyoda, Y. Aoki, Y. Yatsu, M. Hayashi, K. Kawakami, S.
Song, Y. Saito and N. Kawai (Tokyo Tech)  report on behalf of the
MITSuME collaboration:

We observed GRB 111016A (Mangano et al., GCNC 12439) with an optical
three color (g, Rc, and Ic) CCD camera attached to the MITSuME 50 cm
telescope of Akeno Observatory, Yamanashi, Japan.
The follow-up observation was started at 18:52:46, ~15 min after the
BAT trigger.
We did not find any new point source within the enhanced XRT error
circle (Evans et al., GCNC 12441) in all the three bands.

Photometric results are listed below. We used GSC2.3 catalog for flux
calibration.

T0+[sec]      MID-UT     T-EXP[sec]      g'             Rc           Ic
---------------------------------------------------------------------------------
  +942        19:38:33        1380         >17.4      >17.3     >16.5
---------------------------------------------------------------------------------
T0+ : Elapsed time after the burst [sec]
T-EXP: Total Exposure time [sec]

S. B. Cenko (UC Berkeley) reports on behalf of a larger collaboration:

We have imaged the field of GRB111016A (Mangano et al., GCN 12439
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 ) with
the robotic Palomar 60 inch telescope.  Observations began at 11:30 UT on
2011 October 17 (~ 16.9 hours after the initial Swift trigger) and were
obtained in the Sloan r', i', and z' filters.

Inside the revised localization of the X-ray afterglow (Evans et al., GCN
12441
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 ) we marginally detect a source in the i' filter with coordinates:

   RA: 10:15:20.23; Dec: +27:27:44.0 (J2000.0)

Compared with nearby point sources from the Sloan Digital Sky Survey, we
measure a magnitude of i' ~ 22.1 +/- 0.3 mag at this time.  No significant
emission is detected at this location in the r' filter to r' > 21.9 mag.

Given the modest significance of the detection in only a single filter, we
encourage further observations to confirm if this possible source is
indeed the afterglow of GRB111016A.

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), V. Mangano (INAF-IASFPA), D. M. Palmer (LANL),
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 111016A (trigger #505646)
(Mangano, et al., GCN Circ. 12439
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 ).  The BAT ground-calculated position is
RA, Dec = 153.826, 27.474 deg, which is 
   RA(J2000)  =  10h 15m 18.2s 
   Dec(J2000) = +27d 28' 26.7" 
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 64%.
 
The mask-weighted light curve shows a series of slighlty overlapping peaks
starting at ~T-5 sec, peaking at T+58, T+118, T+160, T+210, T+255,
then returning to baseline, followed by smaller peaks at T+410, T+540, T+600,
and possible peaks at T+700 and T+800.  The burst location goes out
of the BAT FOV at T+960 sec.  T90 (15-350 keV) is 550 +- 105 sec
(estimated error including systematics).
 
The time-averaged spectrum from T+35.41 to T+614.48 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.95 +- 0.12.  The fluence in the 15-150 keV band is 4.0 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+115.23 sec in the 15-150 keV band
is 0.9 +- 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/505646/BA/

T. A. Pritchard (PSU) and V. Mangano (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 111016A
188 s after the BAT trigger (Mangano et al., GCN Circ. 12439
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 ).
No optical afterglow consistent with the Enhanced Swift-XRT position
(Evans et al., GCN Circ 12441
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 ) is detected in the initial UVOT exposures,
however a marginal source is detected in followup observations in the
UVOT white filter.  This position is consistent with the source observed by
Cenko et all (GCN Circ 12444
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 ).  Preliminary 3-sigma upper limits and
magnitudes using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC)
exposure and subsequent exposures are:

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

white_FC           188          337          147 >20.3
u_FC               345          595          246 >19.3
white              188        23781         1926 >21.5
white            27360        45216         4662         21.56
v                 4468        16602         1278 >20.5
b                 5288        23264         1967 >21.6
u                  345        22351         1328 >20.4
w1                 724        18207         1095 >20.5
m2                 700        17507         1298 >20.8
w2                 651        12429         1135 >20.7

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).

S. B. Cenko (UC Berkeley), A. Cucchiara (UC Santa Cruz), N. R. Tanvir
(U. Leicester), A. J. Levan (U. Warwick), A. S. Fruchter (STScI), and E.
Berger (Harvard) report on behalf of a larger collaboration:

We have imaged the field of GRB111016A (Mangano et al., GCN 12439
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 ) with
the Near-Infrared Imager and Spectrometer (NIRI) mounted on the 8 m Gemini
North telescope.  Observations were obtained in the J, H, and K filters
beginning at 14:25 UT on 2011 October 17 (~ 19.8 hours after the initial
Swift trigger).

We detect a faint, unresolved source in all three filters coincident with
the optical afterglow candidate from P60 (Cenko et al., GCN 12444
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 ) and
UVOT (Pritchard et al., GCN 12446
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 ).  Having established the reality of
this object, pre-outburst limits from the Sloan Digital Sky Survey imply
some degree of variability and establish it as the optical counterpart of
GRB111016A.

Using the only two 2MASS sources within the NIRI field of view for
calibration, we measure K ~ 20.4 +/- 0.2 (Vega) at this time.  Assuming
limited evolution from the time of the P60 observations, the i' - K color
implies a relatively unusual blue SED (flat spectrum in fnu) when compared
with other GRB afterglows at this time, particularly given the presence of
a modest host galaxy dust column inferred from the X-ray spectrum (Mangano
et al., GCN 12442
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 ).  We caution however, that the photometric calibration
in the NIR remains somewhat uncertain due to the lack of reference sources
in the field.

We wish to thank the entire Gemini staff for the prompt execution
of these observations.  Further observations are encouraged.

M. Blazek (AsU AV), R. Hudec (AsU AV), M. Jelinek (IAA-CSIC), C. 
Polasek (AsU AV) and J. Strobl (AsU AV)

"We observed the field of GRB 111016A (Mangano et al., GCN
12439
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 ) with 0.5m robotic telescope D50 in Ondrejov observatory
(Czech Republic).  The observation started at 01:59:08 UT on
October 17, 2011, approx.  5.5 hours after the Swift trigger.
We report no detection of the optical counterpart on the
unfiltered images within the error circle given by SWIFT-XRT
(Evans et al., GCN 12441
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 ). The upper limit of 19.5 mag in
R-band was estimated using nearby sources from GSC2.2
catalogue."

Atish Kamble, Ralf Kotulla, David Kaplan (UW-Milwaukee), Nial Tanvir, 
K. Wiersema (U. Leicester) and A. Levan (U. Warwick) reports :

We observed the field of GRB 111016A (Mangano et al., GCN 12439
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 ) 
using the WIYN High Resolution Infrared Camera (WHIRC) on the WIYN 3.5m telescope, 
beginning at October 17.5 (UT), approximately 17 hours post-burst. 
Observations were carried out using J, H and Ks bands. We do not detect 
any source within the XRT error circle (Evans et al., GCN 12441
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 ).

The preliminary limiting magnitudes are J = 18.3, H = 17.8 and K = 19.0.

We acknowledge the support from the staff of WIYN-3.5m telescope, and 
especially from Andrew Schechtman-Rook in carrying out these observations.

A. Volnova (SAI MSU), E. Litvinenko (UBAI), I. Molotov (KIAM), A. Pozanenko 
(IKI) on behalf of  larger GRB follow up collaboration report:

We observed the field of the Swift GRB 111016A (Mangano  et al., GCN  12439
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 ) 
with 40-cm telescope ORI-40 of Kitab ISON observatory on Oct. 16 starting on 
(UT) 22:07:26. On the stacked image we do not detect any source within the 
enhanced XRT error box (Evans et al., GCN  12441
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 ). The photometry is based 
on the reference star SDSS  101516.54+272642.0 assuming (after recalibration 
gri->R) R=17.77:

 Tstart UT, T0+,       Filter, Exposure, OT, UL (3 sigma)
                 (mid, d)             (s)

 22:07:26   0.15905  none  36*60       n/d  19.2