GRB 130211A

S. R. Oates (UCL-MSSL), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL),
C. B. Markwardt (NASA/GSFC), K. L. Page (U Leicester) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:

At 03:36:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130211A (trigger=548276).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 147.523, -42.339 which is 
   RA(J2000)  =  09h 50m 05s
   Dec(J2000) = -42d 20' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several overlapping
peaks with a duration of about 20 sec.  The peak count rate
was ~900 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 03:38:26.0 UT, 113.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 147.53605,
-42.34244 which is equivalent to:
   RA(J2000)  = 09h 50m 08.65s
   Dec(J2000) = -42d 20' 32.8"
with an uncertainty of 4.0 arcseconds (radius, 90% containment). This
location is 36 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 2.16
x 10^21 cm^-2 (Kalberla et al. 2005). 

The initial flux in the 2.5 s image was 7.98e-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. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.54. 

Burst Advocate for this burst is S. R. Oates (sro AT mssl.ucl.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.)

F. Knust, J. Greiner, and V. Sudilovsky (all MPE Garching) report on 
behalf of
the GROND team:

We observed the field of GRB 130211A (Swift trigger 548276; Oates et al.,
GCN 14195
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 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).

Observations started at 03:45 UT on 11.02.2013, 9 min after the GRB trigger.
They were performed at a seeing improving over time from 3" to 1.2", and at
an average airmass of 1.0.

We find one variable source inside the 4.0" error circle, at coordinates
RA (2000.0) = 09:50:08.736
Decl (2000.0) = -42:20:32.64
with an error of 0.3".

Based on 1500s exposure in g'r'i'z' and 1200s in JHK started at 06:09 UT,
we estimate preliminary AB magnitudes of:

g' >  25.3 mag,
r' =  23.5 +- 0.1 mag,
i' =  22.2 +- 0.1 mag,
z' =  21.7 +- 0.1 mag,
J =  20.6 +- 0.2 mag,
H =  20.1 +- 0.2 mag, and
K >  19.5 mag.

Given magnitudes are calibrated against GROND zeropoints (g'r'i'z') as well
as 2MASS field stars (JHK) and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.53 mag in
the direction of the burst (Schlegel et al. 1998).

After correcting for the expected foreground extinction, the spectral 
energy distribution of this source
is well-fit by a power-law with slope b~1.4. The reduced flux in g' and 
r' imply a redshift of z~4.3.

T. N. Ukwatta (MSU), 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), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC),
S. R. Oates (UCL-MSSL), D. M. Palmer (LANL), T. Sakamoto (AGU),
G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC)
(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 130211A (trigger #548276)
(Oates, et al., GCN Circ. 14195
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 ).  The BAT ground-calculated position is
RA, Dec = 147.524, -42.330 deg which is 
   RA(J2000)  =  09h 50m 05.7s 
   Dec(J2000) = -42d 19' 47.1" 
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.
 
The mask-weighted light curve shows multiple, weak, overlapping peaks
starting at ~T-10 sec, peaking at ~T-2 sec, and ending at ~T+30 sec.
T90 (15-350 keV) is 25.1 +- 6.3 sec (estimated error including systematics).
 
The time-averaged spectrum from T-1.56 to T+32.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.81 +- 0.24.  The fluence in the 15-150 keV band is 6.4 +- 1.0 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-1.58 sec in the 15-150 keV band
is 0.7 +- 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/548276/BA/

D.N. Burrows (PSU), O.M. Littlejohns (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), B.
Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), J.A. Kennea (PSU), M.C.
Stroh (PSU) and S.R. Oates report on behalf of the Swift-XRT team:

We have analysed 9.2 ks of XRT data for GRB 130211A (Oates  et al. GCN
Circ. 14195
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 ),  from 120 s to 29.1 ks after the	BAT trigger. The data
comprise 201 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The refined XRT position is RA, Dec =
147.53616, -42.34237 which is equivalent to:

RA (J2000): 09 50 08.68
Dec(J2000): -42 20 32.5

with an uncertainty of 3.6 arcsec (radius, 90% confidence).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=2.85 (+0.27, -0.23).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 3.55 (+/-0.14). The
best-fitting absorption column is  5.9 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.2 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 2.5 x 10^-11 (2.3 x 10^-10) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:	     5.9 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 2.2 x 10^21 cm^-2
Excess significance: 15.9 sigma
Photon index:	     3.55 (+/-0.14)

If the light curve continues to decay with a power-law decay index of
2.85, the count rate at T+24 hours will be 1.3 x 10^-7 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.3 x
10^-18 (3.1 x 10^-17) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00548276.

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

S. R. Oates (MSSL-UCL) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130211A
125 s after the BAT trigger (Oates et al., GCN Circ. 14195
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 ).
No optical afterglow consistent with the optical position
(Knust et al. GCN Circ. 14196
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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           125          275          147         >21.8
white              125        17061         1076         >22.9
v                 4470        22933         1646         >21.7
b                 3854        16303         1278         >22.4
u                  284        29091          650         >21.3
w1                4880        28760         1082         >21.8
m2                4674        27853         1175         >21.6
w2                4265        22020         1968         >22.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.53 in the direction of the burst
(Schlegel et al. 1998).

V. Sudilovsky and J. Greiner (both MPE Garching) report on behalf of the 
GROND
team:

Based on follow-up observations taken on 2013-03-29 (T+47 days after the 
initial
Swift trigger 548276; Oates et al., GCN 14195
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 ) of the source reported in GCN
14196
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 , we retract our classification of this object. Since there is no
significant time variability associated with this source, we conclude 
that it
cannot be the afterglow of GRB 130211A.

The final magnitudes of this source (all AB) are:

g' > 24.0 mag,
r' = 23.5 +/- 0.1 mag,
i' = 22.3 +/- 0.1 mag,
z' = 21.7 +/- 0.1 mag,
J = 20.9 +/- 0.2 mag,
H = 20.5 +/- 0.2 mag, and
K > 20.2 mag.

We note that the large r'-i' color is consistent with the 4000 Angstrom 
break
expected from a galaxy at z~0.8. However, we caution that at this time 
there are
not enough data to make a definitive statement about this source.

Given magnitudes are calibrated against GROND zeropoints (g'r'i'z') as 
well as
2MASS field stars (JHK) and are not corrected for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.53 mag 
in the
direction of the burst (Schlegel et al. 1998).