[vsnet-grb-info 4152] GRB 061222B: TAROT La Silla observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5959
SUBJECT: GRB 061222B: TAROT La Silla observatory optical observations
DATE:    06/12/22 05:00:20 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 061222B detected by SWIFT
(trigger 252593) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 149.8s after the GRB trigger
(70.0s after the notice). The elevation of the field increased from
from 70 degrees above horizon and weather conditions
were excellents.

The date of trigger : t0 = 2006-12-22T04:11:02.112

The first image is 30.0s exposure in tracking mode.
We do not detect any OT in the XRT error box
(Racusin et al. 2006 CNC circ. 5957)
with a limiting magnitude of:
t0+149.8s to t0+179.8s : R > 17.9

It must be noticed that the XRT position is near
the star USNO-B1.0 0641-0103283 (R=9.3) that can
masks a faint afterglow on TAROT images.

The second image is 30.0s exposure in tracking mode:
t0+185.4s to t0+215.4s : R > 17.9

We co-added a series of exposures:
t0+149.8s to t0+534.5s : R > 19.9

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

N.B. Galactic coordinates are lon=237.2359 lat= -9.4366
and the galactic extinction in R band is 0.6 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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