[vsnet-grb-info 4135] GRB 061217: TAROT Calern observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5942
SUBJECT: GRB 061217: TAROT Calern observatory optical observations
DATE:    06/12/19 21:54:40 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz at free.fr>

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

We imaged the field of GRB 061217 detected by SWIFT
(trigger 251634) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 20.2s after the GRB trigger
(8.1s after the notice). The elevation of the field increased from
from 24 degrees above horizon and weather conditions
were excellent.

The date of trigger : t0 = 2006-12-17T03:40:07.968

We examined the XRT position provided by
Evans et al. 2006 (GCN Circ. 5932).

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 with a limiting magnitude of:
t0+20.2s to t0+80.2s : R > 16.5

The second image is 30.0s exposure in tracking mode:
t0+87.1s to t0+117.1s : R > 18.1

We co-added a series of exposures:
t0+87.1s to t0+370.6s : R > 19.2

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

We have also images from TAROT La Silla
but they were obtained at lower elevation.
So limiting magnitudes are less high.

N.B. Galactic coordinates are lon=266.5898 lat=+32.4491
and the galactic extinction in R band is 0.1 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.