GCN Circular 8974

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

We imaged the field of GRB 090307A detected by SWIFT
(trigger 345551) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 373.3s after the GRB trigger
The elevation of the field increased from 16 degrees
above horizon and weather conditions were good.

The first image has a duration of 90.0s.
We do not detect any OT at the XRT position
(Evans GCNC 8946) with a limiting magnitude of:
t0+373.3s to t0+463.3s : R > 16.5

We co-added a series of exposures:
t0+373.3s to t0+1062.0s : R > 18.9

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

N.B. Galactic coordinates are lon=348.7859 lat=+15.1296
and the galactic extinction in R band is ~1.4 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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