GCN Circular 3887
Subject
GRB050826: Swift/UVOT early upper limits
Date
2005-08-26T20:18:52Z (19 years ago)
From
Alexander Blustin at MSSL-UCL <ajb@mssl.ucl.ac.uk>
A. J. Blustin (UCL-MSSL), V. Mangano (INAF-IASF),
F. Marshall (GSFC), M. Ajello (MPE), M. Trippico (GSFC-SSAI),
N. Gehrels (GSFC) on behalf of the Swift/UVOT team
The Swift/UVOT began observing the field of GRB050826 at
06:19:55 UT, 105 s after the BAT trigger (Mangano et al.,
GCN 3884). No new source with respect to the DSS image was
detected in the 100 s V-band UVOT Image down to a 3-sigma
upper limit (in the XRT error circle: Mangano et al., GCN
3885) of 17.9 mag.
There was also no optical/UV counterpart detected in summed
images from all filters, down to the following 3-sigma magnitude
upper limits:
Filter T_range (s) Exp (s) 3sig UL
V 105-6545 777 19.4
B 251-16450 1857 21.2
U 236-12331 823 19.0
UVW1 223-11570 968 19.7
UVM2 209-10662 968 19.3
UVW2 266-17318 1818 20.3
Where T_range is the time range post-trigger over which the
summed images were accumulated and Exp is the total exposure time
of the summed image. The magnitude upper limits are not corrected
for extinction.
These magnitudes are based on preliminary zero-points, measured
in orbit, and will require refinement with further calibration.