[vsnet-grb-info 10164] GRB 110128A: TAROT-Calern refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11613
SUBJECT: GRB 110128A: TAROT-Calern refined analysis
DATE:    11/01/28 15:49:13 GMT
FROM:    Bruce Gendre at ASDC  <bruce.gendre at asdc.asi.it>

Laas-Bourez M. (UWA/ICRAR), Gendre B. (ASDC), Atteia J.L. (IRAP-OMP),
Klotz A. (IRAP-OMP), and Boer M. (OHP-OAMP)  report:

following the detection of the optical afterglow by de Ugarte Postigo  
et al. (GCN 11605), we re-analyzed the TAROT data reported in Klotz et  
al. (GCN 11604). At the position of the afterglow, an object is  
marginally detected (2.6 sigma confidence level) within the stack of  
the first two images (73.7s -> 178.6s), with R = 18.0. A stack of the  
following 4 images (193.7s -> 359.2s) gave only an upper limit of R <  
18.7.

Combined with the NOT observation, this gives an optical decay index  
of at least 1.6 during the initial part of the light curve, that could  
indicate the presence of a reverse shock.

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

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