[vsnet-grb-info 13853] GRB 130831A: Montarrenti Observatory optical follow-up

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15167
SUBJECT: GRB 130831A: Montarrenti Observatory optical follow-up
DATE:    13/09/02 12:43:02 GMT
FROM:    Simone Leonini at Monarrenti Obs  <s.leonini at iol.it>

Simone Leonini, G. Guerrini, P. Rosi and L.M. Tinjaca Ramirez (Montarrenti 
Observatory, Siena, Italy) report:

We continue to observe and detect the fading optical afterglow of GRB 130831A 
(Swift trigger 568849, Hagen et al., GCN Circ. 15139) with the automatic 0.53m 
RC 
telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code 
C88).

We stacked 4 unfiltered CCD exposures of 60s each and we detect the very faint 
OT at the same position previously measured (GCN 15150) obtaining the 
following 
photometry at t~34h :

2013 Sep. 01.95733 UT R=20.46 +/- 0.24 

Magnitudes were obtained using Astrometrica software using USNO-B1 catalogue 
for positions and photometry. An ensemble of 66 stars were used for the 
magnitude 
comparison.