TITLE: GCN CIRCULAR NUMBER: 8992 SUBJECT: GRB 090313: Ongoing plateau phase DATE: 09/03/13 23:39:20 GMT FROM: Antonio Deugarte at IAA-CSIC A. de Ugarte Postigo (ESO), J. Gorosabel, A. Sota, A.J. Castro-Tirado (IAA-CSIC) report on behalf of a larger collaboration: We have observed the field of GRB 090313 (Mao et al. GCNC 8980) with the 1.5m OSN telescope (Granada, Spain) starting on 22:29 UT (13.4 hours after the burst). Our I-band images show that the optical afterglow reported by Chornock et al. (GCNC 8979) is still bright. Preliminary photometry yields I=17.7+/- 0.3. This would imply that the plateau phase reported by Perley et al. (GCN 8985) is still ongoing, half a day later. Further observations are encouraged