TITLE:   GCN CIRCULAR
NUMBER:  21076
SUBJECT: GRB 170423A: TAROT Reunion observatory optical observations
DATE:    17/05/07 15:47:33 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz@free.fr>

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.),
Peyrot A., Teng J.P. (Les Makes Observatory, France),
Thierry P. (Auragne Observatory, France),
report:

We imaged the field of GRB 170423A detected by Fermi GBM
(trigger 514660513 / 170423719) with the TAROT robotic telescope (D=18cm)
located at the Reunion observatory, France.

The observations started 7.41h after the GRB trigger.
We stacked 6 images of 120s and examined a field of view of 1.2
degree (radius) around the position provided by
Stanbro et al. (GCNC 21030). We do not see any new source
at the limiting magnitude of:

t0+7.41h to t0+7.62h : Rlim=17.8 +/- 0.2

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.