TITLE: GCN CIRCULAR NUMBER: 15153 SUBJECT: GRB 130831A: optical observations DATE: 13/09/01 01:56:19 GMT FROM: Luca Izzo at ICRA L. Izzo and L. D'Avino report: We have observed the optical afterglow of GRB 130831A using a 0.32m = f/9.3 Ritchey-Chretien telescope of the iTelescope network, at Siding = Spring =96 Australia. We have detected the afterglow in the R and V, but not in the B band. = After an ensemble photometry, using nearby SDSS stars, and correction = from SDSS to V and R filters, we have obtained the following = magnitudes: R =3D 15.58 +- 0.09 (78 min post-trigger =96 240s exposure) V =3D 16.89 +- 0.09 (92 min post-trigger =96 180 s exposure) The R-composite image can be seen at http://blacksabburst.files.wordpress.com/2013/08/r_median.png