TITLE: GCN CIRCULAR NUMBER: 18465 SUBJECT: GRB 151022A: OSN optical upper limit DATE: 15/10/24 11:29:51 GMT FROM: Samantha Oates at MSSL S. R. Oates (IAA-CSIC), S. Jeong (IAA-CSIC/SKKU), V. Casanova, J. C. Tello (IAA-CSIC) and A. J. Castro-Tirado (IAA-CSIC/UMA), report on behalf of a larger collaboration: We observed the field of GRB 151022A (D'Avanzo et al., GCN Circ. 18436) with the 1.5m OSN telescope at Observatorio de Sierra Nevada (Spain). The observations were carried out in the I band on Oct 22.79163 - 22.84025 (4.89 - 6.06 hours post bust). We do not detect any new optical source within the enhanced XRT error circle (Beardmore et al., GCN Circ. 18444) down to a limiting magnitude of I ~21.5 mag.