TITLE:   GCN CIRCULAR
NUMBER:  3276
SUBJECT: GRB 050416: Swift/UVOT detection of afterglow emission
DATE:    05/04/16 19:13:08 GMT
FROM:    Patricia Schady at MSSL/Swift  <ps@mssl.ucl.ac.uk>

P. Schady (MSSL), T. Sakamoto (GSFC/NRC), K. McGowan (MSSL), P. Boyd 
(GSFC/UMBC), P. Roming (PSU), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of 
the Swift UVOT team.

The Swift Ultra-Violet/Optical Telescope (UVOT) began settled observations of 
the field of GRB 050416 (Sakamoto et al; GCN 3264) at 11:05:49 UT, 65s 
after the BAT trigger. A comparison of the 100s finding chart in the V 
filter against the Digitized Sky Survey reverals a new source inside the 
XRT error circle at

RA = 12 33 54.56 Dec = +21 03 27.73

and consistent with the P60 positition reported by Bradley Cenko & Fox (GCN 
3265). The V band magnitude is V = 19.38. The magnitude is based on preliminary 
zero-points, measured in orbit and will require refinement with further 
calibration.

Further detailed analysis is ongoing.