[vsnet-grb-info 13724] GRB130725B: REM-ROS2 optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15039
SUBJECT: GRB130725B: REM-ROS2 optical observations
DATE:    13/07/26 13:48:28 GMT
FROM:    Dino Fugazza at INAF-OAB  <dino.fugazza at brera.inaf.it>

D. Fugazza, S. Covino, G. Tagliaferri (INAF-OAB), V. D'Elia (INAF-OAR) 
report on behalf of the CIBO team:

We observed the field of GRB 130725B (Swenson et al., GCN 15029) 
simultaneously in the optical and near-infrared with the the 60-cm 
robotic telescope REM at La Silla Observatory (Chile). The observations 
started at 23:41:40 UT on July 25 2013, about 6.03 hours after the GRB 
and lasted for about 45 min.
We detect the afterglow reported by Siegel et al. (GCN 15032) and Tanga 
et al. (GCN 15034) with the upgraded ROS2 optical camera. In the NIR 
with REMIR camera the afterglow was not detected.
ROS2 is able to observe simultaneously in the g', r', i', and z' filters 
and preliminary magnitudes (AB) are:

g' = 20.65 ± 0.07
r' = 20.32 ± 0.07
i' = 20.08 ± 0.09

The magnitudes are calibrated against the APASS catalogue.