[vsnet-grb-info 12216] GRB 120807A: TAROT La Silla observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13605
SUBJECT: GRB 120807A: TAROT La Silla observatory optical observations
DATE:    12/08/07 14:39:04 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz at free.fr>

Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR),
Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 120807 detected by SWIFT
(trigger 530267) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 31.5s after the GRB trigger
(15.2s after the notice). The elevation of the field decreased from
8 degrees above horizon and weather conditions
were poor (due to the low elevation).

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 in the enhanced Swift-XRT position
(Evans et al. GCNC 13603) with a limiting magnitude of:
t0+31.5s to t0+91.5s : R > 15.5

Further images does not show OT anymore at about the
same limiting magnitude until 1500 seconds after the
trigger.

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

N.B. Galactic coordinates are lon=333.3260 lat= +3.6420
and the galactic extinction in R band is about 4 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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