TITLE:   GCN CIRCULAR
NUMBER:  17868
SUBJECT: GRB 150523A: LCOGT Cerro-Tololo optical afterglow candidate
DATE:    15/05/24 07:24:01 GMT
FROM:    Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>

S. Dichiara, C. Guidorzi (U. Ferrara), C.G. Mundell (Bath U.),
A. Gomboc (U. Ljubljana) on behalf of a larger collaboration report:

The 1-m LCOGT unit in Cerro Tololo began observing Fermi GBM
and LAT GRB 150523A (Yu et al GCN 17863; Bissaldi et al. GCN 17864)
on May 23 at 23:17 UT (~13.8 hours after the burst trigger)
with SDSS r and i filters.
Inside the Swift-XRT error circle (Beardmore et al GCN 17866)
we detect an uncatalogued object at the following position:

RA(J2000) =   07:41:08.68
Dec(J2000)=  -45:25:12.3

with an uncertainty of ~1" and a magnitude of R=20.2 +-0.1 calibrated
against nearby USNOB-1 stars. Presently we cannot establish whether
the source is fading.