TITLE: GCN CIRCULAR NUMBER: 8333 SUBJECT: GRB 081007, Faulkes Telescope North optical observations DATE: 08/10/07 07:30:58 GMT FROM: James Smith at ARI,Liverpool John Moors U R.J. Smith, A. Melandri, I.A. Steele, D.F. Bersier, C.G. Mundell, (Liverpool JMU), A. Gomboc (Ljubljana), C. Guidorzi (INAF-OAB) on behalf of a larger collaboration reports: The robotic 2m Faulkes Telescope North located in Hawaii observed the field of the GRB 081007 (Baumgartner et al. GCN 8330) starting automatically as soon as the target rose above the observable horizon about 17 minutes after the GRB time. A fading optical source is detected at the XRT position reported by (Baumgartner et al. GCN 8330). Over the period from 0.2 - 1 hour after the burst, the OT is seen to fade in both R and I with a flux power law slope of -0.7. Filter Mag T_mid[min] ----------------------------- R 17.9 +/- 0.4 17.50 R 18.6 +/- 0.4 46.66 I 17.1 +/- 0.4 21.55 I 17.6 +/- 0.4 39.38 ----------------------------- The calibration was performed using the R2 and I magnitudes of the USNOB-1 catalogue field star at 22:39:43 -40:10:15.3 J2000. A equivalent amount of B-band data in which the source is detected have also been obtained and are being analysed. Further observations are ongoing.