GRB 110201A

M. H. Siegel (PSU), A. P. Beardmore (U Leicester),
S. Campana (INAF-OAB), V. D'Elia (ASDC), P. A. Evans (U Leicester),
J. M. Gelbord (PSU), D. Grupe (PSU), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), V. Mangano (INAF-IASFPA),
C. B. Markwardt (NASA/GSFC), C. Pagani (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/IASFPA) and
G. Stratta (ASDC) report on behalf of the Swift Team:

At 09:35:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110201A (trigger=444230).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 137.065, +88.608 which is 
   RA(J2000) = 09h 08m 16s
   Dec(J2000) = +88d 36' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 17 sec.  The peak count rate
was ~4500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 09:36:15.5 UT, 66.6 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 137.5802,
88.6054 which is equivalent to:
   RA(J2000)  = 09h 10m 19.25s
   Dec(J2000) = +88d 36' 19.3"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
location is 45 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 (7.08 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 3.1
(+3.40/-2.79) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
126 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 19.2 mag. The
coverage of the XRT error circle by the 8'x8' region for the list of sources
generated on-board is uncertain because the large number of sources filled the
available telemetry. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.35. 

Burst Advocate for this burst is M. H. Siegel (siegel AT astro.psu.edu). 
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.)

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

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

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

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

MASTER II  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in MASTER-Amur was pointed to the  GRB110201A 21 sec s after 
notice time and 46 sec after GRB time at 2011-02-01 09:35:54.771 UT. On 
our first (10s exposure) set we haven`t found optical transient  within 
SWIFT-XRT error-box.
The 3-sigma upper limit has been about V = 14.5mag
The message may be cited.


mailto: lipunov@sai.msu.ru

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. H. Siegel (PSU),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+878 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110201A (trigger #444230)
(Siegel, et al., GCN Circ. 11622
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 ).  The BAT ground-calculated position is
RA, Dec = 137.489, 88.610 deg, which is 
   RA(J2000)  =  09h 09m 57.3s 
   Dec(J2000) = +88d 36' 36.9" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 97%.
 
The mask-weighted light curve shows 3 or 4 overlapping peaks starting
at ~T-2 sec, peaking at ~T_zero, and ending at ~T+30 sec.
T90 (15-350 keV) is 13.0 +- 2.2 sec (estimated error including systematics).
 
The time-averaged spectrum from T-2.8 to T+13.3 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.09 +- 0.11.  The fluence in the 15-150 keV band is 7.0 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.28 sec in the 15-150 keV band
is 1.1 +- 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/444230/BA/

M. De Pasquale (MSSL-UCL) and M.H Siegel (PSU) report on
behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 110201A 127
s after the BAT trigger (Siegel et al., GCN Circ. 11622
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 ).  No optical
afterglow consistent with the XRT position is detected in the initial
UVOT 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_stop(s)  Exp(s)   Mag

u_FC               127         377     246    >20.0
u                  127        2348     627    >20.4
v                  433        2424     253    >19.5
b                  382        2373     272    >20.4
w1                 482        2324     233    >19.7
m2                 457        2449     233    >19.6
w2                 408        2400     253    >19.1

We note that a bright star (V=7) is a few arcminutes from the
GRB position.

The values quoted above are not corrected for the strong Galactic
extinction due to the reddening of E(B-V) = 0.35 in the direction
of the burst (Schlegel et al. 1998).

D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of the MITSuME collaboration:

We observed the field of GRB 110201A (Siegel et al., GCN 11622
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 )
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.

The observation started on2011-02-01 09:59:39 UT (~25 min.
after the burst). We did not find any new point source within the
XRT error circle (Siegel et al., GCNC 11622) in all the three bands.

Three sigma upper limits of the OT are listed below. We used
GSC2.3 catalog for flux calibration.


T0+[day]   MID-UT   T-EXP[sec]    g'     Rc     Ic
------------------------------------------------------
0.16707    13:35:43  5880.0     >21.3  >21.3  >18.7
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]

D. Grupe and M. H. Siegel (PSU) report on behalf of the Swift-XRT team:


We have analyzed 21 ks of XRT data for GRB 110201A (Siegel  et al. GCN
Circ. 11622
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 ), from 54 s to 83.0 ks after the  BAT trigger. The data
comprise 6 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. 

The light curve can be modeled with  a broken power-law model with an
initial decay slope of alpha-1 = 3.25 (+0.40, -0.66) and a break at
Tbreak-1 = 380 (+120, -55) s. After this break the afterglow decays
with a slope of alpha-2 = 1.03 (+0.12, -0.11).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.04 (+0.26, -0.29). The
best-fitting absorption column is  3.1 (+0.5, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 2.8 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 4.3 x 10^-11 (7.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     3.1 (+0.5, -1.0) x 10^21 cm^-2
Galactic foreground: 2.8 x 10^20 cm^-2
Excess significance: 5.3 sigma
Photon index:	     2.04 (+0.26, -0.29)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00444230.

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

V. Rumyantsev (CrAO), A. Pozanenko (IKI), �A. Volnova (SAI MSU), E.
Klunko (ISTP) report on behalf of larger GRB �follow-up collaboration:

We observed �the field of the Swift GRB 110201A (Siegel et al., GCN
11622
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 ) with Shajn telescope of CrAO in filter R between �Feb. 01 (UT)
17:01 - 18:04, and with AZT-33IK telescope �between Feb. 01 (UT) 16:31
- 17:07. Using stacked image of CrAO observations we detect �a diffuse
source (A) at ~4" offset of a center of the XRT error circle (Siegel
et al., GCN 11622
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 ), see also http://www.swift.ac.uk/sper/444230/. �The
coordinates of the center of the source (A) are (J2000) RA =
09:10:29.84, Dec = �+88:36:17.5 with uncertainty of 0.5" in both
coordinates.

The photometry of the source is based on the USNO-B1.0 star
1786-0003311 (09:12:09.70 +88:36:01.0) assuming R=17.64 is following:

T0+ � � � � Filter, � Exposure, �source A, mag, UpperLimit
(mid, d) � � � � � � �(s)

0.3305 � �R � � � 45x60 � � � � �21.9 +/- 0.1 � � 23.4

Would be the source (A) a host galaxy of GRB 110201A, the galaxy could
be a relatively close �(z <1) taking into account its brightness.
The finding chart can be found at
http://grb.rssi.ru/GRB110201A/GRB110201a_110201_R_ZTSh.gif

M. Onodera (ETH Zurich), E. Daddi (CEA/Saclay), I. Tanaka (Subaru Telescope),
and Y. Yamada (NAOJ) report:

We observed the field of GRB 110201A (Siegel et al., GCN Circ. 11622
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in Ks-band with MOIRCS on the Subaru telescope.

The observations was carried out on 2011-02-02 16:27:33 UT
(~31 hours after the burst) for 200 seconds integration and
on 2011-02-03 16:16:20 UT (~54.5 hours after the burst)
for 520 seconds integration. Within the XRT error circle,
we did not find any evidence for fading sources. On the other hand,
a faint galaxy is detected at (RA, Dec)=(9:10:23.01, +88:36:21.82).
Our preliminary photometry shows the galaxy is Ks=19.7 (Vega) or
Ks=21.5 (AB) with an error of ~0.2 mag.  There is another source
slightly outside of the XRT error circle at (RA, Dec)=(9:10:31.5, +88:36:18.4)
with an magnitude of Ks=19.3 (Vega) or Ks=21.1 (AB) with an error of ~0.15 mag.
Flux calibration was carried out by using 2MASS sources.

Images are provided for consultation at the following web site:
http://www.astro.phys.ethz.ch/people/monodera/grb110201a/