TITLE: GCN CIRCULAR NUMBER: 13114 SUBJECT: GRB 120326A: Swift/UVOT Detection DATE: 12/03/26 13:21:22 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (MSSL-UCL), S. Holland (STScI), and M. H. Siegel (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120326A 67 s after the BAT trigger (Siegel et al., GCN Circ. 13105). A source consistent with the XRT position (Goad et al., GCN Circ. 13110 is detected in the initial UVOT exposures at position: RA (J2000) = 18:15:37.13, Dec (J2000) = +69:15:35.36 or, in decimal degrees: 273.90471, 69.259822 with an uncertainty of 0.5" (90 % confidence). The transient was initially increasing in brightness, and after a small decay rebrightened around 10ks after the trigger. There is also some indication of colour dependence of the time of rebrightening. The detection in the UVOT uvw2 filter gives an upper limit for the redshift of about z < 1.6 for this burst. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 67 217 147 >20.0 white 3903 4103 197 20.16 +/- 0.12 v 4314 5949 393 >19.3 b 3697 5334 393 20.23 +/- 0.16 u 4929 5128 197 19.66 +/- 0.20 m2 4518 16222 1228 >21.2 w2 4109 5744 393 >21.0 w1 9527 10427 886 20.21 +/- 0.18 v 21959 22259 295 18.67 +/- 0.12 w2 21052 21952 886 21.26 +/- 0.32 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).