[AAVSO-HEN] GRB 080603B: TAROT Calern observatory detection of a plateau in the light curve

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TITLE:   GCN CIRCULAR
NUMBER:  7795
SUBJECT: GRB 080603B: TAROT Calern observatory detection of a plateau in the light curve
DATE:    08/06/03 21:54:31 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz at free.fr>

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

We imaged the field of GRB 080603 detected by SWIFT
(trigger 313087) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 62 min after the GRB trigger
(burst occured at the sunset). The elevation of the field
decreased from from 63 degrees above horizon and weather
conditions were good.

We detected the candidate couterpart mentioned by
Rujopakarn et al. (GCNC 7792). We note that the afterglow
stays at about the same magnitude between 68 to 109
minutes. Magnitudes derived from two R filtered images are:

t0+68 min  to t0+ 71 min R=17.4
t0+106 min to t0+109 min R=17.5

The afterglow seems to exhibit a plateau phase
in its optical light curve. We continue the follow-up.

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

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