[vsnet-grb-info 13485] GRB 130606A: TAROT Calern observatory early optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14818
SUBJECT: GRB 130606A: TAROT Calern observatory early optical observations
DATE:    13/06/07 23:34:40 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz at free.fr>

Klotz A. (IRAP-CNRS-OMP), Gendre B. (IRAP-CNRS-OMP),
Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA),
Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 130606A detected by SWIFT
(trigger 557589) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 7.1 min after the GRB trigger
The elevation of the field increased from
63 degrees above horizon and weather conditions
were good.

We detect the optical transient (OT) discovered by
Jelinek et al. (GCNC 14782). TAROT images are unfiltered.
The redshift 5.9 means the OT should emit mainly in the I band.
At the present level of analysis we can not give the
flux of the OT refered in the I band.

We choose the zero point of magnitudes using
the star NOMAD-1 1197-0254828 (R=16.43). We refer the TAROT
magnitudes to the R magnitude of the reference star
(we use CR as the symbol of the clear filtered image
calibrated with the R magnitude of the reference star).

At 7.85 minutes after the GRB, CR=17.1

The OT is measured continuously until 141 minutes
with a mean decay of 0.9.

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