GRB 170115A

K. L. Page (U Leicester), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
A. Cholden-Brown (PSU), C. Gronwall (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/NSF/USRA), F. E. Marshall (NASA/GSFC) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 20:50:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170115A (trigger=733103).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 332.154, +13.781 which is 
   RA(J2000) = 22h 08m 37s
   Dec(J2000) = +13d 46' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve is only immediately
available until T+8 seconds due to a telemetry gap, showing a
rise to a maximum rate of ~800 counts/s at the end of that period. 

The XRT began observing the field at 20:51:39.5 UT, 91.5 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 332.1390, 13.7283 which is equivalent to:
   RA(J2000)  = +22h 08m 33.36s
   Dec(J2000) = +13d 43' 41.9"
with an uncertainty of 6.3 arcseconds (radius, 90% containment). This
location is 196 arcseconds from the BAT onboard position, outside 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 5.14e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 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
0.07. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.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.)

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

Using 615 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 170115A, 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 = 332.13844, +13.72836 which is equivalent
to:

RA (J2000): 22h 08m 33.23s
Dec (J2000): +13d 43' 42.1"

with an uncertainty of 3.7 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.

K.L. Page and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

We have analysed 3.9 ks of XRT data for GRB 170115A, from 82 s to 40.4
ks after the  BAT trigger. The data comprise 224 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 light curve can be modelled with a power-law decay with a decay
index of alpha=1.54 (+0.06, -0.05).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.22 (+0.17, -0.16). The
best-fitting absorption column is  1.3 (+0.5, -0.4) x 10^21 cm^-2, in
excess of the Galactic value of 6.1 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 2.9 x 10^-11 (4.0 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:	     1.3 (+0.5, -0.4) x 10^21 cm^-2
Galactic foreground: 6.1 x 10^20 cm^-2
Excess significance: 2.6 sigma
Photon index:	     2.22 (+0.17, -0.16)

If the light curve continues to decay with a power-law decay index of
1.54, the count rate at T+24 hours will be 4.1 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-14 (1.7 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/00733103.

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

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),

N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), K. L. Page (U Leicester),  T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+450 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170115A (trigger #733103) (Page, et al., GCN Circ. 20462
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 ). The BAT ground-calculated position is RA, Dec = 332.145, 13.750 deg which is RA(J2000) = 22h 08m 34.9s Dec(J2000) = +13d 45' 01.6" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a single FRED-shaped peak, starting at T+0,

peaking at around T+10 sec and decaying to background by around T+50 sec.  The

spacecraft entered the SAA at around T+400 seconds, so there is no data after

this time. T90 (15-350 keV) is 48.0 +- 22.6 sec (estimated error including

systematics).

The time-averaged spectrum from T-7.6 to T+40.4 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.45 +- 0.25.  The fluence in the 15-150 keV band is 4.7 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+15.94 sec in the 15-150 keV band
is 0.2 +- 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/733103/BA/

M. H. Siegel (PSU) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170115A
100 s after the BAT trigger (Page et al., GCN Circ. 20462
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 ).
No optical afterglow consistent with the enhanced XRT position
(Osborne et al. GCN Circ. 20465
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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)         100          250          147         >20.40
white             4804         6335          291         >20.66
v                 5214        35195          816         >19.67
b                 4599        40415          838         >20.68
u (fc)             260          328           67         >18.98
u                 5829         6029          196         >19.65
uvw1              5624         5824          196         >19.32
uvm2              5419         5619          196         >19.37
uvw2              5009        11435          992         >20.69

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.07 in the direction of the burst
(Schlegel et al. 1998).

E. Mazaeva (IKI), A. Pozanenko (IKI), R. Inasaridze (AbAO), A. Volnova 
(IKI),  V. Ayvazian  (AbAO),   O.Kvaratskhelia (AbAO), G. Inasaridze 
(AbAO),  I. Molotov (KIAM), report on behalf of larger GRB follow-up 
collaboration:

We observed the field of the GRB 170115A (Page et al., GCN Circ. 20462
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 ) 
with AS-32 (0.7m) telescope of Abastumani Observatory  on Jan., 16 (UT) 
14:57:24. We obtained several unfiltered images of the field. No source 
is found within enhanced XRT position (Osborne et al. GCN Circ. 20465
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 ).
Preliminary photometry  of the field is following

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

2017-01-16  14:57:24   0.78450   CR     49*60  n/d   n/d 22.5

Photometry is based on nearby SDSS_DR9 stars
SDSS_DR9_id R(Lupton)
J220832.66+134330.8 18.50
J220831.22+134259.5 18.59
J220831.94+134225.7 18.57
J220847.68+134539.9 16.60
J220833.30+133952.6 16.32
J220835.19+134539.0 17.66
J220837.56+134537.8 15.86

K. P. Mooley, 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 
170115A (Page et al., GCN 20462
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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 Jan 16.42, Jan 17.59, Jan 
18.67 and Jan 23.51 (UT) do not reveal any radio source at the XRT 
location (Osborne et al., GCN 20465
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 ), with 3sigma upper limits of 300 
uJy, 78 uJy, 72 uJy and 81 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/.