[vsnet-grb-info 11309] GRB 111225A: TAROT Calern observatory optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12721
SUBJECT: GRB 111225A: TAROT Calern observatory optical observations
DATE:    11/12/25 04:31:51 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz at free.fr>

Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR),
Boer M. (OHP-CNRS), Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 111225A detected by SWIFT
(trigger 510341) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 59.7s after the GRB trigger
(15.5s after the notice). The elevation of the field decreased from
10 degrees above horizon and weather conditions
were good.

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 in the XRT error box (Siegel et al.
CGNC 12720) with a limiting magnitude of:
t0+59.7s to t0+119.7s : R > 15.9

The second image is 30.0s exposure in tracking mode:
t0+134.4s to t0+164.4s : R > 16.2

We co-added a series of exposures:
t0+134.4s to t0+326.7s : R > 18.0

No OT was detected in the next images until
t0+1700s at the level R > 17.6.

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

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