TITLE: GCN CIRCULAR NUMBER: 14750 SUBJECT: GRB 130603A: SON optical observations DATE: 13/06/04 06:39:09 GMT FROM: Arto Oksanen at Nyrola Obs., Finland P. Kehusmaa, A. Oksanen and C. Harlingten report on behalf of the Searchlight Observatory Network: On 2013 June 03, starting at 06:42 UT (T0+42.5 minutes), we observed the field of GRB130603A (Melandri et al., GCN Circ. 14731) with the 0.40 m NM1 telescope located in New Mexico, USA with Apogee Alta U42 CCD for 3x120 seconds using the V filter and 7x120 seconds unfiltered. The afterglow reported by Melandri et. al. (GCNC 14732) is detected in all unfiltered images and in the coadded V band image. We report following differental photometry: UTC (mid) T0+(h) Mag Err Filter ---------------------------------------------------------- 2013-06-03T06:44:21 0.75 18.78 0.13 V 2013-06-03T06:59:55 1.00 18.79 0.07 clear ---------------------------------------------------------- The reference magnitude from the nearby USNO B1.0 star (1729-0016610) with R=16.49. A snapshot showing our coadded unfiltered image can be found at the URL http://pilvi.dyndns.org/arto/GRB130603A_C_840s.jpg