[vsnet-grb-info 8649] GRB 091109B: VLT afterglow confirmation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10156
SUBJECT: GRB 091109B: VLT afterglow confirmation
DATE:    09/11/10 10:00:29 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at astro.ku.dk>

D. Malesani (DARK/NBI), A. de Ugarte Postigo (INAF/OABr), A. J. Levan 
(Univ. Warwick), N. R. Tanvir (Univ. Leicester), J. Hjorth (DARK/NBI), 
P. D'Avanzo (INAF/Brera), report on behalf of a larger collaboration:

Following the observations of GRB 091109B (Oates et al., GCN 10148) with 
the VLT reported by Levan et al. (GCN 10154), we obtained a further 
epoch of R-band imaging with mean time Nov 10.33 UT (10.22 hr after the 
burst), using the same instrument and configuration.

Source "A" by Levan et al. (GCN 10154) is still detected, and decayed by 
1.0+-0.3 mag during this time interval, implying a decay index of alpha 
= 1.7+-0.5. We hence conclude that the source is indeed the afterglow of 
GRB 091109B.

We acknowledge excellent support from the ESO staff at Paranal, in 
particular Alain Smette and Paul Lynam.