GCN Circular 12371
Subject
GRB 110918A: Swift/UVOT Detection of the Optical Counterpart
Date
2011-09-21T03:56:54Z (14 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU), F. E. Marshall (NASA/GSFC), M. De Pasquale (UNLV),
and H. A. Krimm (GSFC/USRA) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110918A
153272 s after the IPN Trigger. A source consistent with the XRT
position (Mangano et al., GCN 12364) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 02:10:09.33 = 32.53887 (deg.)
Dec (J2000) = -27:06:19.6 = -27.10545 (deg.)
with an estimated uncertainty of 0.55 arc sec. (radius, 90% confidence).
Over approximately 18 ks of observation, we do not detect any statistically
significant fading. Additional Swift/UVOT observations are planned.
Preliminary detections using the UVOT photometric
system (Poole et al. 2008, MNRAS, 383, 627) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 153272 154107 791 20.36+-0.13
white 158468 159889 1373 20.16+-0.08
white 163169 165670 2419 20.12+-0.05
white 168950 171166 2178 20.21+-0.06
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).