[vsnet-grb-info 4856] GRB 070628: TAROT La Silla observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6588
SUBJECT: GRB 070628: TAROT La Silla observatory optical observations
DATE:    07/06/29 10:05:31 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 070628 detected by SWIFT
(trigger 283320) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 8.3h after the GRB trigger
(started at the begining of the night).
The elevation of the field decreased from
from 22 degrees above horizon and weather conditions
were good.

We co-added a series of exposures filtered in R, V and I.
We do not detect any OT at the UVOT location
(Gronwall & Holland GCN Circ. 6585):

t0+8.3h to t0+9.1h : R > 17.9

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

N.B. Galactic coordinates are lon=236.5513 lat= +1.2335
and the galactic extinction in R band is 2.4 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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