GRB 051111

T. Sakamoto (GSFC), D. Burrows (PSU), S. Immler (GSFC/USRA),
N. Gehrels (GSFC), S. Hunsberger (PSU), F. Marshall (GSFC),
D. Palmer (LANL), V. La Parola  (INAF-IASFPa)
on behalf of the Swift team:

At 05:59:41 UT, Swift-BAT triggered and located GRB051111  
(trigger=163438).
The BAT on-board calculated location is RA,Dec=348.157,+18.367
{23h 12m 38s,+18d 22' 03"} (J2000), with an uncertainty of 3 arcmin
(radius, 90% containment, stat+sys). The BAT light curve showed a
broad single peak with a 10 second rise to a peak of 4000 counts/s
(15-350 keV) around T+0 with decaying emission at least to T+20.
The spacecraft did not automatically slew due to Moon constraint.

A ToO observation is being planned.

C.G. Mundell (Liverpool JMU), E. Rol (Leicester), C. Guidorzi, A. Gomboc,
I. A. Steele, C.J. Mottram, A. Monfardini, R.J. Smith, D. Carter, M.F.
Bode (Liverpool JMU), P. O'Brien, N. Bannister (Leicester) report:

"The 2-m Faulkes North Telescope robotically followed up GRB051111
(Swift trigger 163438) at 06:04:44 UT.  The automatic "detection mode"
procedure detected a fading candidate at:

23:12:33.17 +18:22:28.80 (J2000) -  R = 14.86 mag (vs USNOB1)

Observations and analysis are ongoing.

This message may be cited"

E.S. Rykoff (U Mich), W. Rujopakarn (U Mich), H. Swan (U Mich), B. 
Schaefer (Louisiana State), S.A. Yost (U Mich), R. Quimby (U Texas), 
report on behalf of the ROTSE collaboration:

A fast fading optical transient has been discovered inside the error 
circle for GRB 051111A (Swift trigger 163438, Sakamoto et al, GCN 4248
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 ) 
by the ROTSE-IIIb telescope, located at McDonald Observatory (see 
Rujopakarn et al, GCN 4247
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 ). The initial response was during the BAT 
emission, when the transient was at 13.0 mag (unfiltered, relative to 
USNO A2.0). The transient faded as a simple power law with decay index ~ 
-0.9. At UT 06:41:57 (t+2500s), the transient was at 17.4 mag.

Continuing observations are in progress.

P. Milne, G. Williams (U. of Arizona), H. S. Park (LLNL), S. Barthelmy 
(GSFC), J. Crist-Lair (Clemson U) , report on behalf of the Super-LOTIS 
collaboration.

The 0.6m automated Super-LOTIS telescope, located at Steward Observatory's 
Kitt Peak site, responded to Swift trigger 163438, GRB051111A.  The first 
image began at 06:00:17.4 UT, 35.9 s after the burst.  We clearly detect 
the OT identified by W. Rujopakarn et al. (GCN 4247
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 ) and find that it has 
faded considerably in images taken 15 minutes after the burst.  The 
approximate R band magnitude in the first 10 second exposure was 
determined using the USNO B1 catalog.

UT Start	Exp Time	R mag	delta R

06:00:17.4	10 s		13.2	0.1

Observations and analysis are continuing.

G. Hill (Keck),  J.X. Prochaska (UCO/Lick),  D. Fox (Penn State),
B. Schaefer (Keck), M. Reed (Keck):

"We have observed GRB 051111 with HIRESr on the Keck telescope
for 1800s starting UT 07:03.  We detect a series of strong MgII,
FeII and SiII absorption features at a redshift z=1.55.  Because we
detect no additional features redward of the MgII doublet, we
adopt this as the redshift of GRB 051111."

A full analysis is underway.

H. Krimm (GSFC/USRA), M. Ajello (MPE), L. Barbier (GSFC), 
S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), 
R. Fink (GSFC), N. Gehrels (GSFC), D. Hullinger (UMD), 
C. Markwardt (GSFC/UMD),D. Palmer (LANL), A. Parsons (GSFC), 
T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC), 
on behalf of the Swift-BAT team:

Using the data set from T-300 to T+300 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 051111 
(trigger #163438)  (Sakamoto, et al., GCN 4248
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 ).  
The BAT ground-calculated position is 
(RA,Dec) = 348.134, +18.365 {23h 12m 32s, 18d 21' 54"} [deg; J2000]
+- 0.8 arcmin, (radius, sys+stat, 90% containment).  
The partial coding was 59%.  

The light curve has a FRED-like structure with the duration of 
the rising and the decay part of 10 sec and 40 sec, respectively.  
The emission might be extended untill T+80 sec.  Although there is 
a bump around T+5s in the 100-350 keV band, this bump is not visible 
below 100 keV.  T90 (15-350 keV) is (47 +- 1) sec 
(estimated error including systematics).  

The power law index of the time-averaged spectrum is 1.32 +- 0.06.  
The fluence in the 15-150 keV band is (3.9 +- 0.1) x 10^-6 erg/cm2.  
The 1-sec peak photon flux measured from T-0.56 sec in the 15-150 keV 
band is (2.5 +- 0.2) ph/cm2/sec.  All the quoted errors are at the 90% 
confidence level.

GRB051111: XRT preliminary analysis

V. La Parola (INAF-IASFPA), V. Mangano (INAF-IASFPA), T. Mineo
(INAF-IASFPA), G. Cusumano (INAF-IASFPA), D. N. Burrows (PSU), F.
Marshall (GSFC), A. Smale (NASA HQ), K. Page (U. Leicester) on behalf of 
the Swift/XRT team:

We have analysed 4 ks of XRT observations of GRB051111
(Sakamoto et al., GCN 4248
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 ). A bright source is well detected.
The refined coordinates for this X-ray afterglow are:

RA(J2000):   23h 12m 33.362s
Dec(J2000):  18d 22' 29.535"

with an estimated uncertainty of 3.5 arcsec (90% containment) and
including the latest XRT boresight correction.
The position is 71 arcsec from the on-board BAT position reported by
Sakamoto et al. and 2.4 arcsec from the optical afterglow first
detected by ROTSE (Rujopakarn  et al., GCN 4247
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 ).

The X-ray light-curve is steeply fading with a slope of -1.9+/-0.2.

The spectrum of the PC data can be modelled with an absorbed power-law
with photon index Gamma = 2.2+/-0.3 (90% containment).
There is a slight evidence for an absorbing column higher than the
Galactic value
(5.02e20 cm^-2) at a level of (9+/-5)e21 cm^-2 at the observed redshift
z=1.55 (Hill et al., GCN 4255
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 ).

The 0.2-10 keV unabsorbed flux at 5000 s  is 1.8e-11 erg cm^-2 s^-1.
At 10000 s the afterglow had faded to flux level of 5.0e-12 erg cm^-2
s^-1.
The predicted flux at T+24h is 8.8e-14erg cm^-2 s^-1

T.S. Poole (UCL-MSSL), T. Sakamoto (GSFC), A.J. Blustin (UCL-MSSL), B.
Hancock (UCL-MSSL) & T.Kennedy (UCL-MSSL) on behalf of the Swift/UVOT team
report:

The Swift-Ultra-Violet/Optical Telescope (UVOT) began observing the field 
of GRB 051111 (BAT Trigger=163438; Sakamoto et al. GCN 4248
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 ) at 2005-11-11
7:47:20, 5560 seconds after the burst. We detect a source in the V, B, U 
and UVW1 filters at position RA 23:12:33.17, DEC 18:22:28.80; this 
position was also reported  by Mundell  et. al. (GCN 4250
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 ).  The source is 
not detected in the UVM2 or UVW2 filters.

The aperture used for optical observations was 6 arcsec, and 12 arcsec was
used for the ultraviolet observations.  The limiting magnitudes are given 
to a 3 sigma limit.

Filter  T_range         T_exp   Mag
         (sec)           (sec)
V       16298-17198     900     19.33+/-0.35    - source detection
B       11237-12136     900     20.38+/-0.35    - source detection
U       10329-11229     900     20.09+/-0.46    - source detection
UVW1    6467-7153       686     20.25+/-0.85    - source detection
UVM2    5560-11832      1800    20.92           - upper limit
UVW2    12145-12938     793     20.64           - upper limit

Where T_range is time post-trigger, and T_exp is the exposure time of the
observation. Magnitude errors include statistical and systematic errors.

These results were obtained from intital UVOT exposures, and the 
observations of GRB051111 are continuing.

This message may be cited.

Ian A. Smith (Rice U) and Heather F. Swan (U Mich) report on 
behalf of the MARGE collaboration:

The Rice University CCD Camera (RUCCD) on the AEOS telescope, 
located at the Maui Space Surveillance System on Haleakala, 
observed the fading counterpart to GRB 051111 (Swift trigger 
163438).  VRI images were taken between 2005-11-11 06:31 UT
(32 minutes after the trigger) and 07:08 UT.  A preliminary 
analysis gives R=17.7 at 07:05 UT in a 30 second exposure.

Dale A. Frail (NRAO) reports on behalf of a larger collaboration:

"We observed the field of the bright GRB 051111 (GCN 4248
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 ) with the
Very Large Array at 8.5 GHz around November 13.15 UT. At the position
of the optical transient (GCN 4247
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 ; GCN 4250
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 ) there is a weak radio
source with a flux density 98 +/- 28 uJy.  We identify this as the radio
afterglow of GRB 051111.

Further observations are planned.

The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."

J.X. Prochaska (UCO/Lick) on behalf of GRAASP reports:

"We have further analyzed the Keck/HIRES spectrum of GRB 051111.
A total integration of 5400s was acquired covering 4200-8400Ang
with a SNR~20 per 1.3km/s pixel at 5500Ang.  The main component
is ~30km/s wide, contains 90% of the gas and is centered at
z=1.54948 +/- 0.00001.  The full line-profile, however, spans
~250km/s.

The gas in the GRB host is remarkable for several reasons:
(1) The SiII 1808 and ZnII 2026, 2062 transitions are saturated
implying log N(Zn) > 13.5 and log N(Si) > 15.9.  We believe these are
the largest Zn and Si column densities recorded outside the Local Group;
(2) The observed Zn/Fe ratio is [Zn/Fe] > 1.2 indicating significant
differential depletion;  (3) We detect the fine-structure SiII* 1816
transition and observe that the weak MgI 2026 transition is saturated.
(4) Perhaps more stunning, we detect nearly every FeII excited  
transition
in the Morton catalog redward of 2300Ang.  This includes several
transitions from the 977K excited level.  These suggest both a large
volume density and a warm gas.

We place a lower limit to N(HI) assuming a solar metallicity for
the gas: log N(HI) > 20.8.  The high metal column density and
significant differential depletion imply a rest-frame V-band
extinction A(V) > 0.5mag.  Adopting the Milky Way extinction curve,
this implies an observed R-band extinction A(R_obs) > 1.4mag.
The extinction is several times larger if one adopts the SMC or
Calzetti curves.

We also identify a very strong intervening MgII system at z=1.18975.

These data were kindly obtained by the Keck observing staff during
engineering and will be publically released.  For now, the raw data
are archived at www.graasp.org."

This GCN may be cited.

D. Nanni, (INAF/Osservatorio di Roma), F. Terra (Second
  University of Rome "Tor Vergata" , C. Bartolini, G. Greco,
  A. Guarnieri, A. Piccioni (Bologna University), R. Poggiani (Pisa
  University), A. De Blasi (INAF/Osservatorio di Bologna) and
  G. Pizzichini (INAF/IASF, Bologna) report:

  We observed the error box of  GRB051111 (Swift trigger 163438)
  with the 152 cm Loiano Telescope and the BFOSC camera system
  in poor sky conditions.
  We obtained the following images, all of them in the Rc filter,
  and detected the optical candidate first reported by Rujopakarn et
  al., GCN 4247
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  with the following magnitudes:

            Start time (UT)  Exposure   Mag
                              (min)
            051111 18:26:55    20      20.0 +- 0.2
            051111 19:31:51    20      20.5 +- 0.3
            051111 22:05:51    20      20.9 +- 0.5
            051111 22:27:31    20      20.9 +- 0.5
            051111 22:50:56    20      21.5 +- 0.8
            051111 23:12:35    20      20.9 +- 0.5

       The coadded images and the observation log will be posted in our
       public directory from where they can be retrieved by sftp using
       hostname: ermione.bo.astro.it, username: publicGRB,

K.Yamaoka, S.Sugita (Aoyama Gakuin U.), M.Ohno, 
T.Takahashi, Y.Fukazawa (Hiroshima U.), 
Y.Terada (RIKEN), K.Abe, Y.Endo, S. Hong, K.Onda, 
M.Tashiro (Saitama U.), K.Nakazawa, G.Sato, 
T.Takahashi (ISAS/JAXA), R.Miyawaki, 
M.Kokubun, K.Makishima (Univ. of Tokyo) and the HXD-II team:

The bright burst, GRB 051111(Krimm et al., GCN4260
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 ), triggered 
the Suzaku Wideband All-sky Monitor (WAM) which covers 
an energy band of 50 keV - 5 MeV at 05:59:39 (UT). 
The observed prompt emission exhibits a FRED-like lightcurve
with a duration (T90) of 31 seconds. 
The fluence in 100 - 700 keV was (8.4 +/- 0.8)X10^-6 erg/cm2. 
The 1-s peak flux was 1.0 +/- 0.1 photons/cm2/s 
in the same energy range.

Preliminary result shows that the time-averaged spectrum 
is well fitted by a single power law with a photon index 
of 1.5 +/- 0.3.

All the quoted errors are at statistical 90% confidence level.
The WAM onboard calibration is still under way,  and 
systematic errors, such as the flux calibration uncertainties of
about 20%, are not included in the errors.

The WAM light curve of this event is available at 
http://www.astro.isas.ac.jp/suzaku/research/HXD-WAM/WAM-GRB/grb/grb_table.html

Further detailed analyses are in progress.

In GCN 4298
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  on GRB051111: Rc optical observations, by D. Nanni et al.,
after the  hostname: ermione.bo.astro.it  and username: publicGRB
for our public directory,  the password: GRB_bo and directory: GRB051111
were omitted.

D. Sharapov, M. Ibrahimov (MAO), A.Pozanenko (IKI),V.Rumyantsev (CrAO) on
behalf of larger GRB follow up collaboration report:

We observed the error box of  GRB051111 (Sakamoto et al., GCN 4248
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 ) with
1.5m telescope of Maidanak Astronomical Observatory. Set of  BR images were
taken between Oct.11 (UT) 18.11 - 18.40. Optical source (Rujopakarn et al.,
GCN 4247
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 ) is detected in a stacked R-image. Preliminary photometry  against
of  USNO A2.0 is following:

Mid time,      Exposure, Filter, Mag.
(UT)             (s)

Nov.11 18:19:35  900     R   19.78 +- 0.14
Nov.11 18:34:51  600     B  >19.0 (3 sigma UL)

The message may be cited.