TITLE:   GCN CIRCULAR
NUMBER:  19923
SUBJECT: GRB 160910A: Swift/UVOT Detection
DATE:    16/09/14 17:12:41 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

L. M. Z. Hagen (PSU) and J. R. Cummings (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160910A
196954 s after the Fermi/GBM (Veres et al., GCN Circ. 19901) and
Fermi/LAT (Racusin et al., GCN Circ. 19902) triggers.  We detect a
fading source consistent with the XRT position (D'Ai et al., GCN Circ.
19904) and optical detections (de Ugarte Postigo et al., GCN Circ.
19907; Malesani et al., GCN Circ. 19908; Lipunov et al., GCN Circ.
19914; Mazaeva et al., GCN Circ. 19919).

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           196954       267060         1620          20.61+-0.14
white           267064       318724         2326          20.95+-0.14

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).