GRB 081003B

D.Gotz (CEA-Saclay), S.Mereghetti, A.Paizis (IASF-Milano),  F. Fontani,
V.Beckmann, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on
behalf of the IBAS Localization Team report:

A GRB lasting about 30 s has been detected by IBAS in IBIS/ISGRI data at
20:48:08 UT of October 3. The coordinates (J2000)  are:

RA = 285.0256 [degrees]
DEC= +16.6914[degrees]

with an uncertainty of 1.5 arcmin (90% c.l.).

A preliminary analysis gives a peak flux in the 20-200 keV range of  
about
3 ph/cmq/s (1-s integration time) and a fluence over the same energy
range of about 6x10e-6 erg/cmq.

A plot of the light curve will be posted at

http://ibas.iasf-milano.inaf.it/IBAS_Results.html

This message can be cited.

Martin Jelinek, Javier Gorosabel, Fran Aceituno, 
Alberto Castro-Tirado (IAA CSIC Granada) and
Antonio de Ugarte Postigo (ESO Santiago)

report on behalf of a larger collaboration:


We observed the error box of the INTEGRAL GRB081003B (Gotz et
al., GCN8317
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 ) with the 30cm BOOTES-1B in El Arenosillo and
with the 1.5m telescope at Observatorio Sierra Nevada.

BOOTES started obtaining unfiltered images at 20:48:49UT (41s
after the GRB trigeer), single images have a detection limit
of ~14 mag. The combination of the first 32 images with an
exposure mean time of 80s after the GRB has a limit of
~17.6mag (calibrated against GSC2). Neither shows any new
sources within the GRB errorbox.

The 1.5m telescope took a single I-band 300s exposure starting
at 21:21:59 (mid exposure ~26.5 min after the GRB), this image
does not reveal any new source in comparison with DSS-IR, but
goes deeper. Further comparison image would be needed to
exploit full potential of this observation.

This message may be cited.

K.L. Page (U. Leicester) & C.B. Markwardt (CRESST/GSFC/UMD) report on 
behalf of the Swift-XRT team:

Swift-XRT performed a Target of Opportunity observation of the INTEGRAL 
GRB 081003B (Gotz et al., GCN Circ. 8317
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 ), starting ~29 ks after the 
trigger. No source is detected within or near to the INTEGRAL error circle 
during a 3.6 ks Photon Counting mode observation. The 3-sigma upper limit 
on the count rate is 0.002 count s^-1, corresponding to an approximate 
observed 0.3-10 keV flux of 1x10^-13 erg cm^-2 s^-1 (using a standard 
counts to flux conversion factor).

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

Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:

We imaged the field of GRB 081003 detected by INTEGRAL
(trigger 5361) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

2008-10-03T20:48:45.809

The observations started 29.7s after the GRB trigger
(7s after the notice) when the gamma emission was
still active. The elevation of the field decreased
from 41 degrees above horizon and weather conditions
were good.

The date of trigger : t0 = 2008-10-03T20:48:16.09

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT at the position provived
by Gotz (GCNC 8317) with a limiting magnitude of:

t0+29.7s to t0+89.7s : R > 16.9

The second image is 30.0s exposure in tracking mode:
t0+97.0s to t0+127.0s : R > 17.4

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon= 48.80 lat= +5.63
and the galactic extinction in R band is 2.0 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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