TITLE:   GCN CIRCULAR
NUMBER:  19122
SUBJECT: GRB 160227A: Swift/UVOT Detection
DATE:    16/02/29 21:48:36 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160227A
161 s after the BAT trigger (Siegel et al., GCN Circ. 19098).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 19104)
is detected in the initial UVOT exposures but had faded away
in later exposures.

The preliminary UVOT position is:
   RA  (J2000) =  12:59:13.80 = 194.80750 (deg.)
   Dec (J2000) = +78:40:45.1  =  78.67920 (deg.)
with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence).

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)         161          311          147         19.34 +/- 0.10
white              600         2418          341         19.80 +/- 0.13 
white             6755         8196          201        >20.82
v                  650         7366          400         19.40 +/- 0.25
b                  575         2393          194         19.71 +/- 0.35
b                 6550         8186          393        >20.10
u (fc)             319          569          245         19.44 +/- 0.20
u                  724         2368          174        >19.22
w1                 699         7776          540        >20.5
m2                1082         7570          432        >21.1
w2                1206         7161          294        >20.7

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).