TITLE: GCN CIRCULAR NUMBER: 9536 SUBJECT: GRB090618: OAA-OAUV Optical observations DATE: 09/06/19 23:05:06 GMT FROM: Alberto Fernandez-Soto at IFCA (CSIC/UC,Santander) A. Fernandez-Soto (IFCA-Santander), V. Peris (OAUV-Valencia), and J. Alonso-Lorite (OAUV-Valencia) report: We have observed the field of GRB090618 (Schady et al., GCN 9512) with the OAUV-0.4m telescope at the Observatorio Astronomico de Aras (OAA) in Aras de Alpuente (Valencia, Spain). Observations began after local sunset on June 18 (UT 19:32, (t-t0)~11.1 hours). We took 23 four-minute exposures using a Johnson R filter. The individual frames have been combined in five groups. The afterglow reported in GCN9512 and confirmed by Cenko et al. (GCN 9513) is clearly detected in all five images, with magnitudes and times: UT(middle) Exposure R Error ---------- -------- ----- ----- 21:30:03 5x4min 18.67 0.14 21:50:51 5x4min 18.57 0.09 22:42:14 4x4min 18.62 0.09 23:21:44 5x4min 18.92 0.13 23:45:19 2x4min 18.96 0.13 All magnitudes have been calibrated using stars in the field and the USNO-B1 catalog (R1 mags). Our results agree with those reported by Cano et al. (GCN 9531), and support the presence of a break in the R-band decay, which happened at (t-t0) ~ 14.6 hours. A lightcurve combining our data and previous GCNs is posted at http://ayalga.uv.es/~fsoto/grb090618 OAA is operated by the Observatori Astronomic de la Universitat de Valencia (OAUV).