TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4553 SUBJECT: GRB 060121: A short-hard GRB in a cluster? DATE: 06/01/22 01:28:37 GMT FROM: Eran Ofek at Tel Aviv U. E. O. Ofek (Caltech) report: The position of the short-hard burst GRB060121 (Arimoto et al. GCN 4550; Prigozhin et al. GCN 4551) is located 10.3 arcmin from the center of the galaxy cluster ZwCl 0906.7+4603. Note, that the probability to find a galaxy cluster in the NED archive, within 10 arcmin from a random position on the celestial sphere (with Galactic latitude |b|>25 deg), is about 5%. A graph of this probability as function of angular distance is available from: http://astro.caltech.edu/~eran/GRB/060121/ProbDistCluster.jpg