TITLE:   GCN CIRCULAR
NUMBER:  15153
SUBJECT: GRB 130831A: optical observations
DATE:    13/09/01 01:56:19 GMT
FROM:    Luca Izzo at ICRA  <Luca.Izzo@ICRA.it>

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