[vsnet-grb-info 13356] GRB 130521A: TAROT La Silla observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14692
SUBJECT: GRB 130521A: TAROT La Silla observatory optical observations
DATE:    13/05/21 23:58:12 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 130521A detected by SWIFT
(trigger 556344) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 33.0s after the GRB trigger
(13.7s after the notice). The elevation of the field decreased from
14 degrees above horizon and weather conditions
were good but the event occured during the dusk
at 28 degrees from the Sun. Due to the twilight the
first image of 60s is saturated.

The second image is 30.0s exposure in tracking mode.
We do not detect any OT in the Swift BAT error box
with a limiting magnitude of:
t0+106.3s to t0+136.3s : Rlim = 15.5

We co-added a series of exposures:
t0+106.3s to t0+1795s : Rlim = 17.3

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

N.B. Galactic coordinates are lon=193.0037 lat= -6.5236
and the galactic extinction in R band is about 1.6 magnitude
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.