TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5003 SUBJECT: GRB060424: optical afterglow detection DATE: 06/04/25 08:25:50 GMT FROM: Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr Christina C. Thoene, Kim Nilsson, Brian L. Jensen, Johan Fynbo (Dark Cosmology Centre) report We observed the BAT error circle of GRB060424 (GCN 5000) in I with the NOT and ALFOSC on La Palma, starting at UT 05:03:40 at very high airmass. Inside the BAT revised error circle (GCN 5001) we detect a new source at the position (J2000) RA = 00:29:25.8 Dec =+36:47:58.7 The preliminary I magnitude obtained from 5x300s stacked images with a mean time of about 1h after the burst is I = 19.1 (compared to a nearby USNO star) The source is not visible in observations obtained the following night and therefore likely to be the afterglow of GRB060424 A finding chart will be available soon at: http://www.astro.ku.dk/~brian_j/grb/grb060424.178/