GRB 150211A

K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University

E. Gorbovskoy, V. Lipunov,  M.Pruzhinskaya, V.Kornilov, D.Kuvshinov, 
N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, 
D.Denisenko, A.Sankovich
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov
Blagoveschensk Educational State University, Blagoveschensk

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

V.Krushinsky, I.Zalozhnih,  A. Popov
Ural Federal University, Yekaterinburg, Kourovka

D.Buckley, S. Potter, A.Kniazev, M.Kotze
South African Astronomical Observatory

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 Tunka was pointed to the  GRB150211A 39 sec after notice time 
and 55 sec after trigger time at 2015-02-11 11:53:08 UT in two 
polarizations. On our first (10s exposure)  set we haven`t found optical transient  within SWIFT error-box 
(ra=16 59 25 dec=+55 22 58 r=0.050000).
The 5-sigma upper limit has been about 15.5 mag
The position hava a high (z~75d) zenith distance.
The observation and data reductions is continued.
The message may be cited.

R. L. C. Starling (U Leicester), S. D. Barthelmy (GSFC),
M. M. Chester (PSU), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU) and
K. L. Page (U Leicester) report on behalf of the Swift Team:

At 11:52:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150211A (trigger=630714).  Swift did not slew because of observing
constraint.  The BAT on-board calculated location is 
RA, Dec 254.856, +55.383, which is 
   RA(J2000)  =  16h 59m 25s
   Dec(J2000) = +55d 22' 59"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several overlapping peaks
structure with a total duration of about 20 sec.  The peak count rate
was ~7000 counts/sec (15-350 keV), at ~4 sec after the trigger. 

Due to an observing constraint, Swift will not slew until T0+33.7
minutes. There will be no XRT or UVOT data until this time. 

The star tracker lost lock about 1 minute before the trigger,
but the location should be good by propagating the gyros.  INTEGRAL-SPIACS
also saw this burst. 

Burst Advocate for this burst is R. L. C. Starling (rlcs1 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.)

S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri
(INAF-OAB) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 150211A at 12:27:22.5 UT,
2111.0 seconds after the BAT trigger. Using promptly downlinked data we
find an uncatalogued X-ray source located at RA, Dec 254.85863,
55.39235 which is equivalent to:
   RA(J2000)  = 16h 59m 26.07s
   Dec(J2000) = +55d 23' 32.5"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 34 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 (1.61 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.1
(+2.58/-2.25) x 10^21 cm^-2 (90% confidence).

M. M. Chester (Penn State) and R. L. C. Starling (U. Leicester) report on 
behalf of the Swift/UVOT team:

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 2115 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 0.02.

Owen Littlejohns (ASU), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer
(UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska
(UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora
Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), Jos�� A. de Diego (UNAM),
Leonid Georgiev (UNAM), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga
(UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report:

We observed the field of GRB 150211A (Starling, et al., GCN 17434
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 )
with the Reionization and Transients Infrared Camera (RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the
Observatorio Astron��mico Nacional on Sierra San Pedro M��rtir from
2015/02 11.50 to 2015/02 11.53 UTC (0.05 to 1.29 hours after the
BAT trigger), obtaining a total of 1.07 hours exposure in the r, i
and z bands.

For a source within the Swift-XRT error circle (Campana, et al.,
GCN 17435
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 ), in comparison with USNO-B1 and 2MASS, we obtain the
following upper limits (3-sigma):

  r     > 23.34
  i     > 23.71
  z     > 20.21

These magnitudes are in the AB system and are not corrected for
Galactic extinction in the direction of the GRB. These upper
limits are consistent with observations by the Swift-UVOT (Chester,
et al, GCN 17436
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 ) and MASTER II robotic telescope (Ivanov, et al,
GCN 17433
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 ).

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.

R. L. C. Starling (U Leicester) reports on behalf of the Swift-XRT
team:

We have analysed 837 s of XRT data for GRB 150211A (Starling et al. GCN
Circ. 17434
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 ), from 2.1 ks to 3.0 ks after the  BAT trigger. The data
are entirely in Photon Counting (PC) mode. The refined XRT position is
RA, Dec = 254.8581, +55.3927 which is equivalent to:

RA (J2000): 16 59 25.94
Dec(J2000): +55 23 33.5

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=1.0 (+/-0.9).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.83 (+0.21, -0.20). The
best-fitting absorption column is  6.2 (+1.6, -1.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 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 4.7 x 10^-11 (7.2 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     6.2 (+1.6, -1.4) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 7.1 sigma
Photon index:	     1.83 (+0.21, -0.20)

If the light curve continues to decay with a power-law decay index of
1.0, the count rate at T+24 hours will be 0.029 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x
10^-12 (2.1 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00630714.

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

E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev 
(ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of 
larger GRB follow-up collaboration:

We observed the field of GRB 150211A (Starling, et al., GCN 17434
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 ) with 
AZT-33IK telescope of Sayan observatory (Mondy). We obtained several 
images in R-filter on Feb., 11,  starting (UT) 12:02:35. Within XRT 
error cirvle (Campana, et al.,GCN 17435)  we do not detect any optical 
source. Upper limit is following

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

2015-02-11 12:02:35   0.03091  R       1800   21.9


The photometry   is based on nearby USNO-B1.0 stars:
USNO-B1.0_id     R2
1453-0255559    18.45
1453-0255560    18.27
1453-0255536    18.49

WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, responded to Swift GRB 150211A (Starling al.,
GCN 17434
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 ) starting at 11:54:12 UT, 121 s after the burst.
Observations were performed with an automatic sequence in the
clear (roughly R), V, and I filters, and the exposure time was
20 s per image. We do not detect any new source in our
images within the refined XRT error circle (Starling et al.,
GCN 17442
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 ). The typical limiting magnitude of our single clear
image is about 18.0 calibrated to USNO B1.0.

W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), R. L. C. Starling (U Leicester), J. Tueller (GSFC), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+242 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 150211A (trigger #630714)
(Starling, et al., GCN Circ. 17434
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 ).  The BAT ground-calculated position is
RA, Dec = 254.846, 55.390 deg, which is 
   RA(J2000)  =  16h 59m 23.0s 
   Dec(J2000) = +55d 23' 23.2" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 16%.
 
The mask-weighted light curve shows several overlapping peaks starting
at ~T-10 sec, peaking at ~T+5 sec, and ending at ~T+30 sec.
T90 (15-350 keV) is 13.6 +- 2.0 sec (estimated error including systematics).
 
The time-averaged spectrum from T-11.24 to T+9.18 sec is best fit
by a Double Blackbody.  This fit gives a kT1 = 7.99 +2.8/-2.1 keV,
kT2 = 24.7 +7.5/-3.2 keV, and (R1/D10)^2 = 6.0 +9.1/-3.3 and
R2/D10)^2 = 0.22 +0.11/-0.15.  (chi squared 74.8 for 59 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 9.9 +- 1.2 x 10^-7 erg/cm2
and the 1-sec peak flux measured from T+4.36 sec in the 15-150 keV band is
12 +- 1 ph/cm2/sec.  A Cutoff PL has an Epeak of 123.4 +- 27.5 keV
(chi squared 81.8 for 56 d.o.f.).  And for completeness, the fit to a
simple power law gives a photon index of 1.28 +- 0.05
(chi squared 107 for 57 d.o.f.).  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/630714/BA/

M. M. Chester (Penn State) and R. L. C. Starling (U Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150211A
2116 s after the BAT trigger (Starling et al., GCN Circ. 17434
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 ).
No optical afterglow consistent with the XRT position (Starling 
GCN Circ. 17442
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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          2116         2266          147         >21.3
white             2116         3123          383         >21.8
v                 2272         8220          255         >20.4
b                 2371         2918          236         >20.1
u                 2346         2713           58         >19.7
w1                2321         2688           58         >19.4
m2                8225         8421          193         >20.4
w2                3129         3243          112         >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).

D. Kawamura, T. Sakamoto, A. Yoshida (AGU) 

We observed the field of GRB 150211A detected by Swift (trigger #630714; 
Starling et al., GCN Circ. 17434
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 ) with the iTelescope.Net (http://www.itelescope.net) 
T11 (0.50 m Plane Wave) telescope located at the New Mexico Skies Observatory (NM, USA).  
20 images of 60 sec exposures were taken in the R filter starting from February 11 12:06:11 (UT) 
about 14.3 minutes after the trigger and stopped on February 11 12:32:17 (UT).  
We do not detect the optical afterglow both in the individual images and the stacked image 
at the enhanced X-ray afterglow position (Starling et al., GCN Circ. 17442
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 ).  The estimated 
five sigma upper limit of the combined image (total exposure of 1200 sec) is ~19.1 using 
the USNO-B1 catalog.

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 150211A (Swift-BAT trigger #630714:
Starling et al., GCN 17434
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 )
triggered Konus-Wind at T0=42728.740 s UT (11:52:08.740).

The KW light curve shows a single multi-peaked emission episode
with a duration of ~13 s.
The emission is visible up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150211_T42728/

As observed by Konus-Wind, the burst had a fluence
of 2.4(-0.3,+0.3)x10^-5 erg/cm2, and a 64-ms peak flux,
measured from T0+7.808 s, of 5.6(-0.7,+0.7)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum (measured from T0 to T0+16.128 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.62 (-0.20,+0.25),
the high energy photon index beta = -2.07 (-0.15,+0.10),
the peak energy Ep = 145 (-24,+30) keV,
chi2 = 114/97 dof.

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

F. V. Ferrante (SMU), T. Guver (Istanbul U), G. Dhungana (SMU), R. Staten (SMU)

and R. Kehoe (SMU) report on behalf of the ROTSE GRB team:

The 0.45-m ROTSE-IIIb telescope, located at McDonald Observatory, Texas,

responded to GRB 150211A (Swift trigger 630714; Starling, et al.,GCN 17434) with

imaging beginning 3.8 s after the GCN notice time. An automated response recorded

the first image at 11:52:43.8 UT, 30.7 s after the burst, under fair observing conditions.

The unfiltered images are calibrated relative to USNO A2.0 (R). We do not detect an

optical source within the refined Swift-XRT error circle (Starling et al., GCN 17442
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 ).

We set the following upper limit:


start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
-----------------------------------------------------------------------------------------------
11:52:43.8   11:53:43.8      60       17.6           30.7               N