TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3823 SUBJECT: GRB 050817: Optical observations DATE: 05/08/17 19:20:46 GMT FROM: Javier Gorosabel at LAEFF-INTA, Madrid P. Tristram (Canterbury Univ. Mt John Observatory), A. de Ugarte Postigo, J. Gorosabel, S. Guzyi, M. JelĂ­nek, A.J. Castro-Tirado(IAA-CSIC), Ph. Yock (Univ. of Auckland) report " We have observed the field of GRB050817 (Fox et al., GCN 3819) with the 0.6m MOA telescope at Mt. John Astronomical Observatory using the wide red and wide blue MOA filters. A combination of 3x300s red-band exposures with mean epoch at 14:18:00 UT (1.97 hours after the burst) shows no new object in the error-box down to a limiting magnitude of 18.5. We note that there is a saturated difraction spike from a nearby star crossing the field which hides aproximately 5% of it." This message can be cited.