TITLE:   GCN CIRCULAR
NUMBER:  16851
SUBJECT: GRB 140928A: LCO-Cerro Tololo observations
DATE:    14/09/29 13:27:52 GMT
FROM:    Drejc Kopac at Math Phys U,Slovenia  <drejc.kopac@fmf.uni-lj.si>

D. Kopac (LJMU), C. Guidorzi (U. Ferrara), C. Mundell (LJMU), on behalf 
of a large collaboration report:

Using the Las Cumbres Observatory Global Telescope Network (LCOGTN) 1-m 
telescope in Cerro Tololo (Chile), we began observing Fermi GRB 140928A, 
which was detected also by the Fermi/LAT (Desiante et al., GCN 16847). 
Optical observations in r' and i' filters (5 x 120s sequences) started 
on September 29 at 05:16:17 UT, i.e. ~18.8 hours after the Fermi/GBM 
trigger.

At the position consistent with the XRT position (Pagani et al., GCN 
16848) and with the GROND position (Varela et al., GCN 16849) we detect 
an un-catalogued source with a preliminary magnitude of R = 20.1 +/- 0.2 
at t_mid = 18.9 hours since the Fermi/GBM trigger time. The magnitude is 
calibrated against nearby USNO-B1 stars.