[AAVSO-HEN] GRB 070612B: Swift/UVOT upper limits

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
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TITLE:   GCN CIRCULAR
NUMBER:  6519
SUBJECT: GRB 070612B: Swift/UVOT upper limits
DATE:    07/06/12 15:15:50 GMT
FROM:    Wayne Landsman at GSFC/SSAI  <landsman at milkyway.gsfc.nasa.gov>

W. Landsman (NASA/GSFC) and D. Grupe (PSU) report on behalf of the 
Swift/UVOT team.

The Swift/UVOT observed the field of GRB 070612B starting 3256 s after 
the BAT trigger (Grupe et al., GCN Circ. 6511).   The UVOT observations 
were delayed due to a Earth-limb constraint. 

We do not find any source in any of the UVOT observations inside the 
refined XRT error circle (Grupe et al., GCN Circ. 6514). The 3-sigma 
upper limits for detecting  a source in the first finding chart (FC) 
exposure and co-added frames are:

Filter    T_start(s)   T_stop(s)     Exp(s)     Mag (3-sigma UL)

Wh  (FC)   3256         3356          98          >20.3

Wh         3256         9882        1201          >21.7
V          3238        11624        1113          >20.0
B          4180         5813         393          >20.4
U          3975         5608         393          >20.1
UVW1       3772         5404         393          >20.1
UVM2       3567         5199         393          >20.0
UVW2       4590        10888        1082          >20.9