GRB 080603

A. Gomboc (U. Ljubljana), I.A. Steele (Liverpool JMU), E. Rol, P. O'Brien 
(U. Leicester), A, Melandri, D. Bersier, C.G. Mundell, R.J. Smith, D. 
Carter, S. 
Kobayashi, M. Burgdorf, M. Bode (Liverpool JMU), C. Guidorzi (INAF-OAB), 
N. Bannister, N. Tanvir 
(U. Leicester) report:

The 2-m Faulkes Telescope North (Hawaii) automatically reacted to the 
INTEGRAL trigger 5283 and possible GRB 080603 and started observing the 
field at 1.3 min after the trigger.

We detect an optical afterglow candidate at:
RA 18:37:38.1,
dec +62:44:39.4.

We estimate the magnitude of the source (calibrated to USNO-B1.0 
catalogue) to be I=20.3+-0.3 at t_0+5.93 min and R=19.6+-0.3 at t_0+7.37 min.

R. Chornock, D. Perley, W. Li, and A. V. Filippenko (UC Berkeley) report that:

The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory slewed to the 
position of GRB 080603 and detected a new source not present in the DSS at 
coordinates:
(J2000)  18:37:38.06  +62:44:39.3

The new source was first detected in a 60s image starting at 11:28:55 UT and is 
near magnitude 18.7 in unfiltered and I band images.

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

A GRB lasting about 180 s has been detected by IBAS in IBIS/ISGRI data at 
11:18:11 UT of June 3. The coordinates (J2000)  are:

 RA:  279.409 [degrees]
 DEC: +62.735 [degrees]

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

A preliminary analysis gives a peak flux in the 20-200 keV range of about 
0.5 ph/cmq/s (1-s integration time) and a fluence over the same energy 
range of about 10e-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.

D. A. Perley, J. S. Bloom (UC Berkeley), and J. X. Prochaska (UCO/Lick) 
report on behalf of a larger collaboration:

Following the KAIT detection (Chornock et al., GCN 7789
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 ) of the 
afterglow candidate of GRB 080603 (Paizis et al., GCN 7790
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 ; Gomboc et 
al., GCN 7788
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 ) we began a spectroscopic sequence at Gemini-North using 
GMOS.  We acquired 2x1200s longslit exposures starting at UT 13:24.  We 
detect very strong resonance lines of MgII and FeII and the 
fine-structure transitions of FeII which establish the redshift of the 
GRB to be z=1.6880.  In addition, we identify intervening MgII 
absorption systems at z=1.5635 (90% c.l.) and z=1.271 (100% c.l.)

In addition, in a single acquisition exposure starting at UT 13:05:05 
(107 minutes after the trigger) the object has a magnitude (relative to 
USNO B1.0) of R~19.7, suggesting it has not faded significantly since 
the observations of Gomboc et al. (GCN 7788
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 ).

We thank Richard McDermid and the Gemini staff and for support.

P.A. Milne (U Arizona) and A. Updike (Clemson U) report on behalf of the
Super-LOTIS team:

The 0.6m Super-LOTIS telescope began R-band observations of the error
region of GRB080603 at 11:19:04 UT.  The OT detected by Gomboc et al.
(GCN 7788
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 ) and Chornock et al. (GCN 7789
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 ) is not
apparent in the initial images, but is clearly visible in
subsequent images. Using a stack of 10 x 60sec images obtained between
11:22:44 -> 11:33:46, we estimate the magnitude of the source to be
R=19.3 +/- 0.3.

We used the USNO-B star at RA=18:37:55, Dec=+62:44:32 to derive the
R2 magnitude.

Analysis continues to better characterize the rise of the emission from
the OT.

This message can be cited.