TITLE:   GCN CIRCULAR
NUMBER:  16810
SUBJECT: GRB 140907A: 1.23m CAHA optical observations
DATE:    14/09/10 00:32:37 GMT
FROM:    Javier Gorosabel at IAA-CSIC  <jgu@iaa.es>

J. Ugarte (UPV-EHU), S. Perez-Hoyos (UPV-EHU), A. Sanchez-Lavega
(UPV-EHU), R. Hueso (UPV-EHU), J. Gorosabel (IAA-CSIC/UPV-EHU) report on
behalf of the BEGIRA project:

We observed the GRB 140907A (GCN 16788) optical afterglow (GCN 16789, GCN
16791, GCN 16792, GCN 16793, GCN 16797, GCN 16800, GCN 16802, GCN 16803,
GCN 16804, GCN 16806, GCN 16809) with the 1.23m CAHA telescope. The
observations were carried out in the R and I-bands on Sep 8.96168-9.21435
UT (30.96-37.05 hours post GRB). The optical afterglow is clearly detected
with a magnitude I(Vega)=21.4, calibrated against the USNO B1.0 catalog.