GCN Circular 3384
A. de Ugarte Postigo, A.J. Castro-Tirado (IAA-CSIC Granada), A. Eigenbrod (EPF de Lausanne), M. Jelinek, J. Gorosabel and S. Guziy (IAA-CSIC Granada), report: "Following the detection by Swift-BAT of the short gamma-ray burst GRB 050509b (Hurkett et al. GCN 3381), we have obtained two R-band images (300s exposure time each) with the 1.2m Mercator telescope at Roque de los Muchachos Observatory in La Palma, starting at 04:36:02 UT (i.e. 35.88. min after the onset of the burst). The location was observed under poor seeing conditions, at very high airmass. We do not identify any source within the error box provided by Swift-XRT (Kennea et al. GCN 3383) down to magnitude 21." This message may be cited.