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GCN Circular 5861

Subject
GRB 061126: Swift/UVOT Observations
Date
2006-11-26T19:28:23Z (17 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL/UCL) and B. Sbarufatti (INAF-IASFPA) report on behalf of the 
Swift/UVOT team:

The Swift/UVOT began observing the field of GRB 061121 at 09:14:41 on 
2006-11-26, 27.6 minutes after the BAT trigger (Sbarufatti et al., GCN 5854). 
An optical counterpart is detected in the V, B, U, UVW1 and UVM2 filters, as 
well as in the White-band filter (160-650 nm) at a position consistent with 
that reported by Vanden Berk et al. (GCN 5856). We can, therefore, put a 
photometric upper limit on the redshift of GRB 061126 of z < ~1.5.

The photometry results for each UVOT filter are given below where Tmid is 
the average time of the exposure, in seconds, since the BAT trigger. For those 
filters in which the afterglow is detected we report the magnitude of the 
afterglow in the first and last exposures taken before the spacecraft slewed to 
another target 4.3hrs after the BAT trigger. The upper limit (3 sigma) reported 
for the UVW2 filter is taken from a co-added exposure and for all detections 
that are less than 3-sigma above background, the significance of the detection 
is given. The quoted errors do not include the 0.1 mag systematic uncertainty 
in the photometric zero points.

   Filter   Tmid    Exposure  Mag  Err
              (s)     (s)
==========================================
   V         3423     197     19.29 0.58 (1.9 sigma)
             9178     295     19.86 0.78 (1.4 sigma)

   B         2809     197     19.75 0.24
             7097     197     21.04 0.75 (1.5 sigma)

   U         7702     197     19.54 0.27
             15331    110     > 18.72

   UVW1      5664     279     19.34 0.37
             14515    886     > 20.04

   UVM2      3627     197     19.79 0.56
             13608    886     21.38 0.85 (1.3 sigma)

   UVW2      5767     393     > 20.00

   White     1655     98      18.50 0.12
             8111     197     19.72 0.22
==========================================

The values quoted above are not corrected for the expected Galactic
extinction of E_{B-V} = 0.18 mag (Schlegel et al. 1998).
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