GCN Circular 15724

Subject
GRB 140110A: Swift/UVOT Observations
Event
Date
2014-01-11T18:28:39Z (12 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates  (UCL-MSSL) and M. Stamatikos (OSU) report on behalf of the Swift/UVOT team:

The Swift/UVOT observed the error circle of the Fermi/LAT GRB 140110A 
(Bissaldi et al., GCN Circ. 15714Loading...
 
 ) in a series of u band observations 
tiled on the sky. The total exposure time is 12.7 ks spread over 7 
fields; each field was observed typically for 1.8 ks. Observations 
started 28.4 ks after the Fermi/LAT trigger. At the locations of the 
XRT candidates (Maselli et al., GCN Circ. 15721Loading...
 
 ), we find sources 
2 and 6 lie outside of the UVOT field of view, while the rest are 
consistent with known objects within the USNO-B1 catalogue. 
However, within the UVOT fields we find two uncatalogued sources:

The refined UVOT position for UVOT source 1 is:

    RA (J2000)   1:57:11.98
   Dec (J2000) -36:17:48.2

The refined UVOT position for UVOT source 2 is:

    RA (J2000)   1:55:13.95
   Dec (J2000) -35:54:14.0

both positions have an estimated uncertainty of 0.6 arcsec (radius, 90% confidence). 
At this time we are unable to determine if either of these sources are fading. 

Preliminary magnitudes for the two UVOT uncatalogued sources using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

Source   Filter       T_start(s)   T_stop(s)      Exp(s)         Mag

UVOT1    u           28798        30607          1734  19.63 +/- 0.10 
UVOT2    u           30251        63599          1793  19.56 +/- 0.10 

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).