GRB 110223A

T. Sakamoto (NASA/UMBC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
P. A. Evans (U Leicester), J. M. Gelbord (PSU),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), E. Sonbas (GSFC/USRA/Adiyaman Univ.),
M. Stamatikos (OSU/NASA/GSFC) and C. A. Swenson (PSU) report on behalf
of the Swift Team:

At 20:56:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110223A (trigger=446674).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 345.599, +87.567 which is 
   RA(J2000)  =  23h 02m 24s
   Dec(J2000) = +87d 34' 03"
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 5 sec.  The peak count rate
was ~1600 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 20:58:27.8 UT, 88.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 345.85923, 87.55851 which
is equivalent to:
   RA(J2000)  = 23h 03m 26.22s
   Dec(J2000) = +87d 33' 30.6"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 50 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 (5.61 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.5
(+1.82/-1.63) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 8.97e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 97 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
0.34. 

Burst Advocate for this burst is T. Sakamoto (Taka.Sakamoto 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.)

M. Jelinek, (IAA-CSIC), A. de Ugarte Postigo (DARK/NBI), 
P. Kubanek and A.J. Castro-Tirado (IAA-CSIC) 
on behalf of a larger collaboration report:

   We have observed the afterglow of GRB 110223A (Sakamoto 
et al., GCNC 11753) with the 0.6m TELMA/BOOTES-2 located in
Malaga (Spain). R-band observations began 228 seconds after
the burst. We do not detect any source within the XRT error
box down to the following detection limits, as compared with
the USNO-B1.0 catalogue:

exp start(t-t0)	integration	3-sigma limit
228		3		15.4
228     	669		17.6
930		1035		18.0

This message can be cited.

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

Using 539 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 110223A, 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 = 345.85354, +87.55766 which is equivalent
to:

RA (J2000): 23h 03m 24.85s
Dec (J2000): +87d 33' 27.6"

with an uncertainty of 2.0 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.

O. M. Littlejohns (U. Leicester) and T. Sakamoto (NASA/UMBC) report on
behalf of the Swift-XRT team:

We have analysed 2.7 ks of XRT data for GRB 110223A (Sakamoto  et al.
GCN Circ. 11753
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 ), from 78 s to 29.6 ks after the  BAT trigger. The data
comprise 40 s in Windowed Timing (WT) mode (the first 8 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 Evans et
al. (GCN. Circ 11759).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.96 (+0.50, -0.27), followed by a break at T+386 s to
an alpha of 0.52 (+0.15, -0.16).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.4 (+0.4, -0.3). The
best-fitting absorption column is  2.3 (+0.9, -0.8) x 10^21 cm^-2, in
excess of the Galactic value of 5.6 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.4 x 10^-11 (6.6 x 10^-11) erg
cm^-2 count^-1.

A summary of the PC-mode spectrum is thus:
Total column:	     2.3 (+0.9, -0.8) x 10^21 cm^-2
Galactic foreground: 5.6 x 10^20 cm^-2
Excess significance: 4.5 sigma
Photon index:	     2.4 (+0.4, -0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00446674.

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

C. Guidorzi (U. Ferrara), A. Melandri (INAF-OAB),
I.A. Steele, C.G. Mundell, S. Kobayashi (Liverpool JMU),
A. Gomboc (U. Ljubljana) on behalf of a large collaboration report:

The 2-m Liverpool Telescope automatically began observing
GRB 110223A (Sakamoto et al. GCN Circ. 11753
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 ) on February 23,
20:59:47 UT, 2.8 minutes from the GRB trigger time with the
SDSS filters riz.
Within the UVOT-enhanced XRT error circle (Evans et al.,
GCN Circ. 11759
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 ) we do not find any source down to the following
limiting magnitudes.

Mid time from      Tot Exposure    Filter   Limiting Magnitude
trigger (s)           (s)
------------------------------------------------------------
1920                  780           r > 22.2
2320                  720           i > 21.6
2620                  720           z > 19
------------------------------------------------------------

Calibration is against some nearby USNOB-1 stars (R2 and I magnitudes).
However, we note the presence of an uncatalogued source at

RA  =  23:03:20.31,
Dec = +87:33:29.3 (J2000),

lying 3.4" from the XRT centre with the following magnitudes:

r = 21.6 +- 0.1
i = 20.9 +- 0.1

This source does not exhibit any fading during the observations.

M.Sokolowski,T.Batsch,A.Majcher,A.Majczyna,K.Nawrocki,J.Uzycki,G.Wrochna (SINS, Swierk),
M.Cwiok,W.Dominik,L.W.Piotrowski,A.F.Zarnecki (University of Warsaw),
K.Malek,L.Mankiewicz,R.Opiela,M.Siudek,V.Repei (CFT PAN),
G.Kasprowicz,M.Zaremba (Warsaw University of Technology),
from the "Pi of the Sky" collaboration ( http://grb.fuw.edu.pl ).
M. Jelinek and A. J.Castro-Tirado (IAA-CSIC Granada) on behalf of a larger collaboration.

The wide field "Pi of the Sky North" apparatus installed in the BOOTES-1
station at ESAt/INTA-CEDEA in Mazagon (Huelva, Spain; 
http://grb.fuw.edu.pl/pi/index.html#piinta_site.htm )
started observing position of GRB 110223A 25 seconds after BAT trigger,
165 seconds after the burst. No new source has been identified on 10s exposures
nor on the sums of images corresponding to 50s exposure. 
Following limits were obtained:

t_start - t0      start (UT)  end (UT)     3-sigma limit

    165            20:59:44  - 20:59:54        11.0

    165            20:59:44  - 21:00:45        12.0


where limits are based on the reference star magnitudo in V filter.

W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), 
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt 
(GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos 
(OSU/NASA/GSFC), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+300 sec from the recent telemetry downlink, 
we report further analysis of BAT GRB 110223A (trigger #446674) 
(Sakamoto, et al., GCN Circ. 11753
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 ).  The BAT ground-calculated position is 
RA, Dec = 345.386, 87.586 deg which is 
   RA(J2000)  =  23h 01m 32.7s 
   Dec(J2000) = +87d 35' 11.3" 
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
 
The mask-weighted light curve shows a FRED-like peak at ~T+0.5 sec. T90 (15-350 keV) 
is 7.0 +- 2.2 sec (estimated error including systematics).
 
The time-averaged spectrum from T+0.1 to T+8.1 sec is best fit by a simple 
power-law model.  The power law index of the time-averaged spectrum is 
1.70 +- 0.33.  The fluence in the 15-150 keV band is 1.6 +- 0.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+0.08 sec in the 15-150 keV band is 
0.6 +- 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/446674/BA/

V.Yurkov, Yu.Sergienko, D.Varda, I.Kudelina
Blagoveschensk Educational State University, Blagoveschensk

K.Ivanov, O.Chuvalaev, V.Poleschuk, E.Konstantinov, V.Lenok, O.Gres,
S.Yazev, N.M.Budnev,
Irkutsk State University

E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina,
D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov,
D.Zimnukhov, M. Kornilov, V.Shumkov, S.Shurpakov
Sternberg Astronomical Institute, Moscow State University

V.Krushinski, I.Zalozhnich, A. Popov
Ural State University, Kourovka

A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik
Kislovodsk Solar Station of the Pulkovo Observatory

MASTER II  robotic telescopes (MASTER-Net: http://observ.pereplet.ru) 
located in  Amur-Blagoveschensk  was pointed to the GRB110223A 7sec after 
notice time and  147 sec after GRB time.
Unfortunately, main telescopes was not  in focus.
But we have images from Very Wide Filed Cameras mounted on telescope. 
On our first (5s exposure) set 
we haven`t found optical transient  within SWIFT-BAT error-box 
(Littlejohns et al., GCN Curc 11761) brighter 12 mag (unfiltered).
12   coaded first images give limit 13 mag (mean time ~ 177 sec after 
trigger).

The message may be cited.
The first image is available at 
http://observ.pereplet.ru/images/GRB110223A/first.jpg
There is Polar star at right  botom  angle of the image.

mailto: lipunov@sai.msu.ru

M. De Pasquale (MSSL-UCL) and T. Sakamoto (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 110223A
97 s after the BAT trigger (Sakamoto et al., GCN Circ. 11753
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 ).
No optical afterglow consistent with the XRT enhanced position
(Evans et al., GCN circ. 11759
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 ) is detected in the initial UVOT exposures
nor in the summed exposures.
Preliminary 3-sigma upper limits 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_end(s)   Exp     Magnitude

white (fc)        97          246     147	>20.81
white             97         5588     344	>21.16

v                639         5998     217	>19.40

b                565         5383     216	>20.00

u (fc)           310          559     196	>19.41
u                310         5177     443	>20.15

uw1             4773         6408     393	>20.13

um2              663         6203     412	>20.14

uw2              615         5794     216	>19.89

The above magnitudes are not corrected for the strong Galactic
extinction along the line of sight, corresponding to E(B-V) = 0.34
(Schlegel et al. 1998).

V. Rumyantsev(CrAO), N. Pit (CrAO), A. Pozanenko (IKI) report on
behalf of larger �GRB �follow-up collaboration:

We observed �the field of the Swift GRB 110223A (Sakamoto et al., GCN
11753
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 ) with AZT-11 telescope of CrAO starting on Feb. 23 (UT) 22:44
and under
seeing of about 2.2 arsces. In the enhanced Swift-XRT position �(Evans
et al., GCN 11759
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 ) we do not detect any object. We also do not detect
the uncatalogued source reported by Guidorzi et al., GCN 11762
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 . The
photometry is based on the USNO B1.0 star 1775-0024257 (23 03 42.29
+87 32 38.4) assuming R=17.73.

T0+ � � �Filter, � Exposure, mag.
(mid, d) � � � � � � �(s)

0.0965 �R 21x180 � � � >21.5 (3 sigma)

The finding chart can be found at
http://grb.rssi.ru/GRB110223A/GRB110223A_110223_azt11.gif