[vsnet-grb-info 4628] GRB 070508: TAROT La Silla observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6384
SUBJECT: GRB 070508: TAROT La Silla observatory optical observations
DATE:    07/05/08 05:11:57 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 070508 detected by SWIFT
(trigger 278854) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 829s after the GRB trigger
(6s after the notice). The elevation of the field increased from
from 28 degrees above horizon and weather conditions
were good.

The date of trigger : t0 = 2007-05-08T04:18:17.6

The first image is 90.0s exposure in tracking mode
with no filter.
We do not detect the UVOT candidate couterpart mentioned
by Grupe et al. (GCNC 6383) with a limiting magnitude of:
t0+829s to t0+919s : R > 17.8

We co-added a series of exposures with no filter:
t0+829s to t0+1704s : R > 19.7

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

N.B. Galactic coordinates are lon=314.8792 lat=-32.4208
and the galactic extinction in R band is 0.1 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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