TITLE: GCN CIRCULAR NUMBER: 19465 SUBJECT: GRB 160525B: Swift/UVOT Detection DATE: 16/05/25 20:09:20 GMT FROM: Massimiliano de Pasquale at IASF-Palermo M. De Pasquale, N.P. Kuin (UCL-MSSL) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160525B 88 s after the BAT trigger (Krimm et al., GCN Circ. 19459). A source consistent with the XRT position (Evans GCN Circ. 19460) is detected in the initial UVOT white filter exposure. 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 88 238 147 19.8 +/- 0.3 white 581 1894 284 >20.9 v 631 1945 156 >18.9 b 556 1870 136 >19.8 u 300 2018 379 >20.0 w1 680 1996 156 >19.5 m2 1603 1795 39 >18.2 w2 606 1573 58 >18.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). -- Dr. Massimiliano De Pasquale Research associate - Swift UVOT scientist Mullard Space Science Laboratory, University College London