GRB 051105B

E. Distefano, S. Piranomonte, E. Molinari, G. Chincarini, F.M. Zerbi, M. 
Rodono', S. Covino, V. Testa, G. Tosti, F. Vitali, L.A. Antonelli, P. 
Conconi, G. Cutispoto, G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, 
P. Goldoni, on behalf of the REM/ROSS Team report:

On Nov 05, 2005 the field of GRB051105B (Mereghetti et al. GCN4192
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 )
has been observed with the REM telescope located in La Silla (Chile).

The field was imaged with ROSS REM instrument in R, V and I filters 
starting at 2005-11-06T02:20:58 UT (approximately 1 hour
after the burst) for a total integration time of 120 seconds for each 
filter.

No sources are detected within IBAS Integral error circle (Mereghetti et 
al. GCN4192
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 ) down to a limiting magnitude of 17.9, 17.1, 18.4 
respectively (3-sigma upper limit).

T. Mineo (INAF-IASF PA), S. Campana (INAF-OAB),
G. Chincarini (INAF-OAB and UNIMIB), D. Malesani (SISSA),
A. Moretti (INAF-OAB), P. Romano (INAF-OAB),
G. Tagliaferri (INAF-OAB) on behalf of the Swift XRT team

The Swift/XRT  began observing the field of GRB 051105B
on 2005-11-07 at 16:41:31 UT, about 2.25 days after the
INTEGRAL trigger (GCN 4192
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 ; Mereghetti et al.). 
A weak X-ray source is detected at RA(2000)=00h 37m 53.7s'
Dec(2000)=-40d 29m 14s,  with an estimated uncertainty
of 7 arcsec (90% containment), including corrections
for the XRT boresight offset. This source is 3.7 arcsec away
from the bright star HD 3516, which we identify as the optical
counterpart.  No other X-ray source is detected within the BAT
error circle.  The 3 sigma upper limit is 1.1E-03 cts/s corresponding
to an unabsorbed 0.2-10 keV flux of 5E-14 erg cm^-2 s^-1, assuming
a power-law model with  an energy index slope of -1 and a
Galactic absorbing column  of 3.0E20 cm^-2.

A. J. Blustin (UCL-MSSL), S. Campana (OAB/ASDC), J. Nousek (PSU),
N. White (GSFC), N. Gehrels (GSFC) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began observing the field of GRB 051105B on
2005-11-05 at 11:05:50 UT, ~2.25 days after the INTEGRAL trigger
(Mereghetti et al., GCN 4192
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 ). No new source with respect to the
DSS is observed within the 2 arcminute radius IBAS error circle
in coadded V-band exposures down to the following 5-sigma
magnitude upper limit:

Filter  T_range(days)  Exp(sec)  5sigUL
V       2.25-2.38      4932      20.4

We note that there was a high image background in the region of
the IBIS error circle due to the presence of a Vmag=9 star within
it (as mentioned by Torii, GCN 4193
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 ).

K. Torii (Osaka U.) reports on behalf of the ART collaboration:

 The error region of the INTEGRAL GRB 051105b (Mereghetti et
al. GCN4192
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 ) was observed by the 14 inch Automated Response Telescope. 
Imaging started at 2005 November 5, 11:07:29 UT (94 s after the
trigger) and 60 s integration in Ic band was repeated. Early data
suffered from low transparency.

 We note a bright star, SAO 215170 (V=9.0), within the INTEGRAL error
circle. While no new object is identified and the following upper
limits are derived for an optical afterglow.

------------------------------------------
StartUT	Filter	Mag	Nframes
------------------------------------------
11:19:21 Ic	> 7.3	1
11:24:42 Ic	>10.7	2
------------------------------------------

S. Mereghetti (IASF, Milano), D.Gotz (CEA, Saclay), N. Mowlavi, S. Shaw, 
M. Beck, A. Neronov, J.Soldan (ISDC, Versoix) and J. Borkowski (CAMK, 
Torun) on behalf of the IBAS Localization Team report:

A 20 s long GRB has been detected by IBAS in IBIS/ISGRI data at 11:05:50 
UT on November 5 2005.
Its refined coordinates (J2000) are:

RA:    9.4771 [degrees]
DEC: -40.4812 [degrees]

with an uncertainty of 2 arcmin (90% c.l. radius).

A plot of the light curve will be posted at

http://ibas.mi.iasf.cnr.it/IBAS_Results.html

This message can be cited.

K. Kinugasa (Gunma Astronomical Observatory) and K. Torii (Osaka U.) report:

 The error region of the INTEGRAL trigger #2701 was imaged by the
robotic 0.25m GETS telescope in the Gunma Astronomical Observatory.
Unfiltered imaging started at 11:14:11 UT (304 s after the trigger)
and 30 s integration was repeated.

Preliminary analysis does not show a new object within the refined
2'.82 radius error region (Seq_Num 1) and the following upper limits
are derived.

------------------------------------------
StartUT  Limit  Nframes
------------------------------------------
11:14:11 >11.2  1
11:28:40 >15.0  21
------------------------------------------

We note a bright (9th magnitude) star, SAO 215170, within the INTEGRAL
error circle.