TITLE: GCN CIRCULAR NUMBER: 10609 SUBJECT: GRB 100414A: Swift/UVOT Observations DATE: 10/04/17 15:56:44 GMT FROM: Wayne Landsman at GSFC/SSAI W. Landsman (GSFC) and J. Cannizzo (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began observations of the field of GRB 100414A 40.4 hours after the Fermi LAT and GBM-detected trigger (Takahashi et al. GCN Circ. 10594, Foley et al., GCN Circ. 10595). We detect the source reported by Cucchiara & Fox (GCN Circ. 10606, 10608) and Filgas et al. (GCN Circ. 10607) Combining our white observations into exposures beginning at 40.4 and 53.2 hours, we find evidence for source fading. Filter T_start (hr) Exp(s) Mag Err White 40.38 765 20.54 +/- 0.10 White 53.20 3531 20.86 +/- 0.06 These observations are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998). The photometry is on the UVOT photometric system described in Poole et al.(2008, MNRAS, 383,627).