[vsnet-grb-info 7162] GRB 081228: TAROT Calern observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8743
SUBJECT: GRB 081228: TAROT Calern observatory optical observations
DATE:    08/12/28 02:01:57 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz at free.fr>

Klotz, A. (CESR-OMP), Gendre, B. (OAMP),
Boer M. (OHP), Atteia J.L. (LATT-OMP) report:

We imaged the field of GRB 081228 detected by SWIFT
(trigger 338338) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 24.7s after the GRB trigger
(6.1s after the notice). The elevation of the field decreased
from 24 degrees above horizon and weather conditions
were good.

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT in the XRT error box (Page et al.
GCNC 8742) with a limiting magnitude of:
t0+24.7s to t0+84.7s : R > 16.9

The second image is 30.0s exposure in tracking mode:
t0+91.8s to t0+121.8s : R > 17.4

We co-added a series of exposures:
t0+91.8s to t0+384.6s : R > 18.4

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

N.B. Galactic coordinates are lon=148.4290 lat=-26.7069
and the galactic extinction in R band is 0.4 magnitude
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.