GCN Circular 20254

Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:

We imaged the field of GRB 161214A detected by INTEGRAL
(trigger 7644) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 24.6s after the GRB trigger
(17.7s after the notice). The elevation of the field increased from
45 degrees above horizon and weather conditions
were good until the end of the night.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).

We detected the couterpart mentioned by Guidorzi
et al. (GCNC 20252). The optical afterglow reached flux peak
at t0+240s (+/- 15s). The early light curve:

t0 +  25 s to t0 +   85s  : Rlim = 16.6 (trailed image)
t0 +  99 s to t0 +  211s  : Rlim = 17.1
t0 + 222 s to t0 +  293s  : R    = 16.9 +/- 0.3
t0 + 304 s to t0 +  899s  : R    = 17.4 +/- 0.3
t0 + 910 s to t0 + 2180s  : R    = 18.7 +/- 0.4

Magnitudes were estimated with the nearby star
NOMAD-1 0968-0244492 ra=190.7246097 dec=+06.8741839
R=15.04.

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

N.B. Galactic coordinates are lon=296.86 lat=+69.60
and the galactic extinction in R band is about 0.1 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.