TITLE: GCN CIRCULAR NUMBER: 23626 SUBJECT: GRB 190106A: Swift/UVOT Detection DATE: 19/01/06 21:43:23 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 190106A 90 s after the BAT trigger (Sonbas et al., GCN Circ. 23615). A source consistent with the XRT position (Goad et al. GCN Circ. 23619) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 01:59:31.16 = 29.87985 (deg.) Dec (J2000) = +23:50:43.9 = 23.84552 (deg.) with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence). The source was also detected by MASTER (Yurkov et al, GCN Circ. 23614,23616), MITSuME (Itoh et al, GCN Circ. 23617), GMG (Mao et al, GCN Circ. 23618), TSHAO (Reva et al, GCN Circ. 23620), GWAC-F60B (Xin et al, GCN Circ. 23622), Xinglong (Zhu et al, GCN Circ. 23623) who report a redshift of z~0.896 and Bassano Bresciano Observatory (Quadri et al, GCN Circ. 23624). Preliminary detections 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 90 240 147 16.64 +/- 0.03 v 633 653 20 16.54 +/- 0.16 b 559 579 20 16.70 +/- 0.09 u 304 553 246 15.97 +/- 0.03 w1 682 702 20 17.36 +/- 0.29 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998).