TITLE: GCN CIRCULAR NUMBER: 8989 SUBJECT: GRB 090313: Faulkes Telescope North observations DATE: 09/03/13 18:53:56 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), A. Melandri, I. A. Steele (Liverpool JMU), A. Gomboc (U. Ljubljana), D. Bersier, C.J. Mottram, C.G. Mundell, R.J. Smith (Liverpool JMU), P. O'Brien, N. Bannister, N. Tanvir (U. Leicester) on behalf of a large collaboration report: The 2-m Faulkes Telescope North (Hawaii) automatically reacted to the Swift burst GRB 090313 (trigger=346386, Mao et al. GCN 8980). Observations started about 168 s after the trigger time with filters BRi. We confirm the detection of the optical counterpart (Chornock et al. GCN 8979, Updike et al. GCN 8983, Perley et al. GCN 8985). The afterglow magnitude was observed to rise and peak around 1.3 ks post burst, followed by a rapid decay out to ~ 10 ks. Further observations suggest a subsequent flattening. Filter Tmid(s) Exposure(s) Mag ------------------------------------------------ R 880 60 16.12 +/- 0.07 R 1260 120 15.60 +/- 0.05 R 12290 300 18.20 +/- 0.20 ------------------------------------------------ Magnitudes are calibrated with respect to the nearby USNOB1 star 13:13:35.789 +08:05:24.11 assuming its catalogue value of R2=17.08. Further observations are going to be attempted.