TITLE:   GCN CIRCULAR
NUMBER:  19051
SUBJECT: Further Swift/UVOT observations of GRB 160220B
DATE:    16/02/22 13:52:57 GMT
FROM:    Massimiliano de Pasquale at IASF-Palermo  <m.depasquale@ucl.ac.uk>

M. De Pasquale, A.A. Breeveld (MSSL-UCL) and J. Cummings
(GSFC/UMBC) report on behalf of the Swift/UVOT team:

Following the detection of a source at the southern edge of the 1.5''
Swift-XRT error circle (Evans et al. GCN circ. 19033) by GROND
(Wiseman and Greiner, GCN Circ. 19042) we have re-analysed
our UVOT observations We caution that the anlysis is complicated
by a crowded field and large noise.

About at the sourthern edge of the XRT error circle we detect a source

RA = 17h 19m 27.64s (259.86517)
Dec = -18d 07m 30 s (-18.12500)

with an error of ~1''. The position of this source is
copatible with that of the oject detected by GROND.

Magnitudes of this source are given in the table below.

Filter         T_start(s)  T_stop(s)  Exp(s)     Mag
v              4145        10454       1082   18.7 +/- 0.2
b              3530         5165        393   19.4 +/- 0.2

The same source is detected  in successive exposures:

v              39730       62085       1072   18.7 +/- 0.2
b              44464       45371        885   19.4 +/- 0.2


As the source does not seem to have changed in brightness, we do
not think it is the optical afterglow of GRB160220B.

Magnitudes above are given in the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373).

[GCN OPS NOTE(22feb16): Per Circ 19053, the Subject-line
has been corrected from "20A" to "20B".]