[AAVSO-HEN] GRB 070412: TAROT Calern observatory optical observations

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TITLE:   GCN CIRCULAR
NUMBER:  6488
SUBJECT: GRB 070412: TAROT Calern observatory optical observations
DATE:    07/06/08 05:52:32 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 070412 detected by SWIFT
(trigger 275119) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.
Analysis of this burst is late due to a technichal
problem.

The observations started 676.6s after the GRB trigger
(4.4s after the notice). The elevation of the field decreased from
from 53 degrees above horizon and weather conditions
were very good.

The date of trigger : t0 = 2007-04-12T01:27:03.744

The first image is 90.0s exposure in tracking mode:
We do not detect any OT in the XRT location
(Romano et al. 2007 GCNC 6273)
with a limiting magnitude of:
t0+676.6s to t0+766.6s : R > 18.5

We co-added a series of exposures:
t0+676.6s to t0+1251.3s : R > 19.5

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

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