GRB 130102A

K. L. Page (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
F. E. Marshall (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 18:10:53 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130102A (trigger=544784).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 311.464, +49.835 which is 
   RA(J2000)  =  20h 45m 51s
   Dec(J2000) = +49d 50' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As per usual for an image trigger, the TDRSS
lightcurve does not show anything significant. 

The XRT began observing the field at 18:12:50.3 UT, 116.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
311.4233, 49.8174 which is equivalent to:
   RA(J2000)  = 20h 45m 41.60s
   Dec(J2000) = +49d 49' 02.6"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 113 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 consistent with the Galactic value of 7.96
x 10^21 cm^-2 (Kalberla et al. 2005). 

The initial flux in the 2.5 s image was 5.62e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 125 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 large, but uncertain extinction expected. 

We note that this event is at galactic coordinates: l = 88.33 deg, b = 4.22 
deg.  It has the characteristics of a GRB, but could be a galactic transient 
since it is close to the galactic plane. 

Burst Advocate for this burst is K. L. Page (kpa AT star.le.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. Gorosabel (IAA-CSIC) & L. Toribio (IAC), report on behalf of a larger
collaboration:

"We observed the Swift/XRT location of GRB 130102A (Page et al., GCNC
14127) using the 82cm IAC80 telescope at the Observatorio del Teide
(Tenerife, Spain). We took a set of I-band images on Jan 2.7924--2.8340 UT
(0.84--1.83 hours post burst). No optical source brighter than I~21 (Vega)
is detected inside the XRT error circle."

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

Using 1933 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 130102A, 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 = 311.42346, +49.81764 which is equivalent
to:

RA (J2000): 20h 45m 41.63s
Dec (J2000): +49d 49' 03.5"

with an uncertainty of 1.6 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.

P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M.C. Stroh (PSU), D.N.
Burrows (PSU), J.A. Kennea (PSU), C. Pagani (U. Leicester), A.P.
Beardmore (U. Leicester), A. Maselli  (INAF-IASFPA) and K.L. Page
report on behalf of the Swift-XRT team:

We have analysed 10 ks of XRT data for GRB 130102A (Page  et al. GCN
Circ. 14127
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 ),  from 109 s to 24.6 ks after the	BAT trigger. The data
comprise 66 s in Windowed Timing (WT) mode (the first 5 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 Osborne et
al. (GCN. Circ 14129).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=1.33 (+0.21, -0.20). At T+456 s  the decay
steepens to an alpha of 5.5 (+1.9, -1.2) before breaking again at T+924
s to a final decay with index alpha=0.88 (+0.31, -0.28).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.0 (+0.4, -0.3). The
best-fitting absorption column is  1.13 (+0.34, -0.29) x 10^22 cm^-2,
in excess of the Galactic value of 8.0 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 5.8 x 10^-11 (1.2 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.13 (+0.34, -0.29) x 10^22 cm^-2
Galactic foreground: 8.0 x 10^21 cm^-2
Excess significance: 1.9 sigma
Photon index:	     2.0 (+0.4, -0.3)

If the light curve continues to decay with a power-law decay index of
0.88, the count rate at T+24 hours will be 5.2 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x
10^-14 (6.4 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/00544784.

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

E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, 
N.Shatskiy, P.Balanutsa,  A.Kuznetsov, V.V.Chazov, D.Denisenko

Lomonosov Moscow State University, Sternberg 
Astronomical Institute

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
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

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)


MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in 
Kislovodsk was pointed to the  GRB130102A (Page et. al. GCN14127
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 )   104 
sec after GRB time at 2013-01-02 18:12:37 UT in 
two  polarizations. On our first (20s exposure) set we haven`t found 
optical transient  within SWIFT  error-box.
The 5-sigma upper limit has been about 17.9 mag

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located near Blagoveschensk was pointed to the  GRB130102A (Page et. al. 
GCN 14127
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 )   107
sec after GRB time at 2013-01-02 18:12:40 UT in
two  diagonal polarizations. On our first (20s exposure) set we haven`t 
found optical transient  within SWIFT  error-box.
The 5-sigma upper limit has been about 13.9 mag. The low limit is the 
resultsa of the high zenit distance.

We note that there are no objects in any catalogs 10" around center of 
the Swift XRT error box (Osborne et. al. GCN 14129
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 ).

The message may be cited.

C. B. Markwardt (GSFC), 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), K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), 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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130102A (trigger #544784)
(Page, et al., GCN Circ. 14127
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 ).  The BAT ground-calculated position is
RA, Dec = 311.435, 49.838 deg which is 
   RA(J2000)  =  20h 45m 44.4s 
   Dec(J2000) = +49d 50' 16.4" 
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 99%.
 
The mask-weighted light curve shows a peak starting at ~T+10 sec, peaking 
at ~T+22 sec, and ending around T+180 sec.  There is a possibility
of emission out to at least T+230 sec.  T90 (15-350 keV) is 77.5 +- 18.2 sec
(estimated error including systematics).
 
The time-averaged spectrum from T+12.51 to T+100.43 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.39 +- 0.18.  The fluence in the 15-150 keV band is 7.2 +- 0.9 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+23.54 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/544784/BA/

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

We have imaged the field of GRB130102A (Page et al., GCN 14127
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 ) with the
robotic Palomar 60 inch telescope (P60).  Observations began at 01:56 on
2013 January 3 (~ 7.8 hours after the Swift trigger), and were obtained
under poor seeing conditions in the r', i', and z' filters.

We do not detect any sources within the enhanced XRT error localization
(Osborne et al., GCN 14129
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 ).  Using nearby point sources from the AAVSO
Photometric All-Sky Survey (APASS) for calibration, we measure limiting
magnitudes of r' > 20.9, i' > 20.5 at this time.  We note that these
limits do not include a correction for the large Galactic extinction along
this line of sight.

T. A. Pritchard (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 130102A
126 s after the BAT trigger (Page et al., GCN Circ. 14127
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 ).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 14129
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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           126          276          147         >21.1
u_FC               284          534          246         >20.4
white              126         7587          844         >22.4
v                  614        12045         1343         >20.9
b                  540         7382          549         >20.8
u                  284         7177          775         >20.5
w1                 664         6972          549         >20.2
m2                 639        12641          934         >20.7
w2                 590         7794          568         >20.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.90 in the direction of the burst
(Schlegel et al. 1998).