[vsnet-grb-info 3672] GRB 060904: TAROT optical observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5506
SUBJECT: GRB 060904: TAROT optical observations
DATE:    06/09/04 02:51:49 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 060904 detected by SWIFT
(trigger 227996) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

First image was acquired 26.8s after the GRB trigger
(9.4s after the notice). The field elevation decreased from
10 degrees above horizon and weather conditions
were excellents. First image was acquired during
the prompt phase.

Date of trigger : t0 = 2006-09-04T01:03:21.600

First image is 60.0 exposure trailed. No OT is visible
in the XRT error box (Grupe et al. GCNC 5502)
t0+26.8s to t0+86.8s : R > 16.0

Second image is 30.0 exposure. No OT is visible:
t0+93.7s to t0+123.7s : R > 17.3

We co-added a series of exposures. No OT is visible:
t0+93.7s to t0+376.2s : R > 19.5

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

N.B. Galactic coordinates are lon= 71.6566 lat=+50.2105
and the galactic extinction in R band is 0.0 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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