GRB 161022A

M. Stamatikos (OSU/NASA/GSFC), S. D. Barthelmy (GSFC),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL) and T. N. Ukwatta (LANL)
report on behalf of the Swift Team:

At 02:43:40 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 161022A (trigger=718655).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 128.967, +54.365 which is 
   RA(J2000)  =  08h 35m 52s
   Dec(J2000) = +54d 21' 54"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a single peak
with a duration of about 20 sec.  The peak count rate
was ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 02:45:53.4 UT, 133.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 129.00074, 54.34876 which is equivalent
to:
   RA(J2000)  = 08h 36m 00.18s
   Dec(J2000) = +54d 20' 55.5"
with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 91 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 (4.13 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.2
(+1.30/-1.19) x 10^21 cm^-2 (90% confidence). 

No UVOT data are available at this time. 

Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 AT nasa.gov). 
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.)

P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Using  promptly downlinked XRT event data for GRB 161022A, we find an
enhanced XRT position of the afterglow: RA, Dec: 129.0018, 54.3490
which is equivalent to:
   RA (J2000)  = 08 36 00.44
   Dec (J2000) = +54 20 56.3
with an uncertainty of 2.0 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/718655.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

This circular 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 161022A detected by SWIFT
(trigger 718655) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 71s after the GRB trigger
(17s after the notice). The elevation of the field increased
from 56 degrees above horizon and weather conditions
were excellents.

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+71.2s to t0+131.2s : Rlim = 17.4

The second image is 30.0s exposure in tracking mode:
t0+146.3s to t0+176.3s : Rlim = 18.5

We co-added a series of exposures:
t0+146.3s to t0+442.9s : Rlim = 19.0

No more OT detection until t0+6800s at Rlim = 19.0.

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

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

The 2-m Liverpool Telescope began observing Swift GRB161022A (Stamatikos 
et al., GCN 20087
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 ) with the RINGO3 polarimeter on October 22, 02:46:59 
UT (199 s since trigger). Within the prompt enhanced XRT error circle 
(Evans et al. GCN 20088
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 ) we found nothing brighter than 20.5 mag in the 
SDSS-R filter at a mid time of 35 minutes post burst.

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

We have analysed 8.7 ks of XRT data for GRB 161022A (Stamatikos et al.
GCN Circ. 20087
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 ), from 118 s to 22.5 ks after the  BAT trigger. The
data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The best
available XRT position	(using the promptly downlinked event data, the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue) is RA, Dec = 129.0017, 54.3486 which is equivalent to:

RA (J2000): 08 36 00.40
Dec(J2000): +54 20 55.0

with an uncertainty of 2.0 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.46 (+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 1.70 (+0.16, -0.07). The
best-fitting absorption column is  consistent with the Galactic value
of 4.1 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 (4.0 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     4.1 (+/-2.0) x 10^20 cm^-2
Galactic foreground: 4.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.70 (+0.16, -0.07)

If the light curve continues to decay with a power-law decay index of
1.46, the count rate at T+24 hours will be 1.5 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.6 x
10^-15 (5.9 x 10^-15) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00718655.

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

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

Using 1530 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 161022A, 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 = 129.00148, +54.34828 which is equivalent
to:

RA (J2000): 08h 36m 0.35s
Dec (J2000): +54d 20' 53.8"

with an uncertainty of 1.4 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. Malesani (DARK/NBI and DTU Space) and J. Prieto-Arranz (IAC) report 
on behalf of a larger collaboration:

We observed the field of GRB 161022A (Stamatikos et al., GCN 20087
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 ) 
using the Nordic Optical Telescope (NOT) equipped with the AlFOSC 
imaging camera. Observations started on 2016 Oct 22.161 UT, 68.5 min 
after the GRB, and consisted of 2x300 s exposures in the SDSS r band. 
Observations were affected by adverse weather conditions.

Within or in the proximity of the XRT error circle (Evans, GCN 20088
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 ), 
at a mid time of 73.9 min after the GRB trigger, we detect no new 
sources down to a limiting magnitude r > 22 (AB), calibrated against 
nearby SDSS stars.

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

At 02:43:45.92 UT on October 22nd, 2016, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 161022A
(trigger 498797029/161022114), which was also detected by Swift
(Stamatikos et al., GCN 20087
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 ). The GBM on-ground location is
consistent with the Swift position. The angle from the Fermi LAT
boresight is 131 degrees.

The GBM light curve shows a weak, FRED-like peak with a duration
(T90) of about 19 s (50-300 keV). The time-averaged spectrum
from T0-6.1 s to T0+11.3 s is adequately fit by a power law function
with an exponential high-energy cutoff. The power law index is
-0.59 +/- 0.37 and the cutoff energy, parameterized as Epeak,
is 155.7 +/- 33.2 keV

The event fluence (10-1000 keV) in this time interval is
(1.65 +/- 0.24)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.3 s in the 10-1000keV band is 2.5 +/- 0.4 ph/s/cm^2.

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

L. M. Z. Hagen (PSU) and M. Stamatikos (OSU/NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 161022A
137 s after the BAT trigger (Stamatikos et al., GCN Circ. 20087
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 ). No
optical afterglow consistent with the XRT position (Evans et al. GCN
Circ. 20094
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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 early exposures are:

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

white              137         1544          539         >21.25
u                  296         1668          333         >19.90
b                  551         1692           99         >19.27
v                  627         1421           97         >18.34
uvw1               676         1644          116         >18.86
uvm2               824         1272           38         >17.99
uvw2               602         1570          116         >19.10


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).

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI),
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 161022A (Stamatikos et al., GCN Circ.
20087
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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 2016/10 22.37 to
2016/10 22.53 UTC (6.23 to 9.89 hours after the BAT trigger), obtaining
a total of 2.49 hours exposure in the r and i bands and 1.04 hours
exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle (D'Elia et al., GCN Circ.
20092
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 ), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain
the following 3-sigma upper limits:

  r	> 24.24
  i	> 24.04
  Z	> 22.96
  Y	> 22.50
  J	> 22.18
  H	> 21.87

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

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

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), 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-239 to T+737 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 161022A (trigger #718655)
(Stamatikos, et al., GCN Circ. 20087
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 ).  The BAT ground-calculated position is
RA, Dec = 128.988, 54.366 deg, which is 
   RA(J2000)  =  08h 35m 57.2s 
   Dec(J2000) = +54d 21' 57.8" 
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 14%.
 
The mask-weighted light curve shows a few overlapping peaks starting at ~T-1 sec,
peaking at ~T+2 sec, an ending at ~T+15 sec.
T90 (15-350 keV) is 7.3 +- 1.0 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.53 to T+8.24 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.14 +- 0.21.  The fluence in the 15-150 keV band is 7.5 +- 1.0 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+2.13 sec in the 15-150 keV band
is 1.6 +- 0.4 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/718655/BA/

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. 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 
161022A (Stamatikos et al., GCN 20087
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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 Oct 22.15, Oct 23.26, Oct 
26.22 and Oct 29.31 (UT) do not reveal any radio source at the XRT 
location (Evans et al., GCN 20094
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 ), with 3sigma upper limits of 135 uJy, 
93 uJy, 105 uJy and 105 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/.