[vsnet-grb-info 13045] GRB 130418A: TAROT Calern and TAROT la Silla observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14382
SUBJECT: GRB 130418A: TAROT Calern and TAROT la Silla observatory optical observations
DATE:    13/04/19 00:34:28 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 130418A detected by SWIFT
(trigger 553847) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

Continuous observations started 78.7 min after the GRB trigger
due to the dusk. The elevation of the field
decreased from 58 degrees above horizon and weather conditions
were good. Four hours after the TAROT la Silla telescope
(Chile) started to observe.

The afterglow mentioned by De Pasquale (GCNC 14377)
appears clearly in the images.

The following magnitudes are obtained using the star
NOMAD-1 1036-0179295 (ra=149.0472378 dec=+13.6557094
R=14.91) for flux calibration:

  Start   Stop    Rmag
  (min)   (min)
    78.7   84.7  17.34
    88.4   94.4  17.48
    98.2  110.2  17.59
   117.6  141.6  17.91
   156.6  186.6  18.11
   242.1  263.1  18.13

Considering a flux decay power law the corresponding
exponent is alpha=0.65.

Magnitudes are not corrected for galactic dust extinction.

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