TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3386 SUBJECT: GRB 050509b: PAIRITEL and WIYN Observations DATE: 05/05/09 07:21:27 GMT FROM: Josh Bloom at Harvard/CFA J. Bloom (UCB), C. Blake (Harvard), J. X. Prochaska (UCSC), J. Hennawi (UCB), M. Gladders (Carnegie), B. Koester (U Michigan) report: "We find no new point sources at the XRT position (3380) of the GRB 050509b (3381) in RIJHK (WIYN+PAIRITEL). Based I and R imaging and JHK imaging of the XRT position of GRB 050509b, however, there appears (to the West of the XRT) a bright extended galaxy at ra 12:36:12.90, dec +28:58:58.8 (J2000) (=2MASS 2MASX J12361286+2858580), with J=15.25, H=14.46, K=14.09 mag. Although the XRT is ~10 arcsec from this galaxy, at the photometric redshift of the cluster (z=~0.22), this is only 35 kpc h_71^{-1} in projection. Thus, we find a plausible association of this short burst with the outskirts a nearby, potential host galaxy. This message may be cited.