GCN Circular 7804
N. P. M. Kuin (MSSL/UCL), and V. Mangano (INAF), report on behalf of the Swift UVOT team The Swift UltraViolet/Optical Telescope (UVOT) began observations of INTEGRAL burst GRB080603A (INTEGRAL trigger number 5283, Paizis et al., GCN Circ. 7790), on June 3, 2008, at 14:11:20 UT, 173 minutes after the initial trigger in the UVOT v filter. We detect a fading source at position : RA=18:37:38.21 Dec=+62:44:38.40 (279.40921 +62.74400 ddeg (J2000)). The initial magnitude observed for GRB080603A is given below for the first observation in the UVOT v filters: Filter Tstart(s) Tstop(s) Exp(s) Magnitude v 10389 10499 109. 19.16 +/- 0.35 The magnitude decrease observed was 1.2 magnitudes per hour. The values quoted above are on the UVOT Photometric System (Poole et al, 2008, MNRAS 383,627). They are not corrected for the expected galactic reddening of E(B-V) = 0.044 in the direction of the burst (Schlegel et al. 1998).