[vsnet-grb-info 11654] GRB 120311B: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13047
SUBJECT: GRB 120311B: Swift/UVOT Upper Limits
DATE:    12/03/12 12:15:09 GMT
FROM:    Alice Breeveld at MSSL-UCL  <aab at mssl.ucl.ac.uk>

A. A. Breeveld (MSSL-UCL) and F. E. Marshall (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 120311B
3072 s after the BAT trigger (Marshall et al., GCN Circ. 13038).
No optical afterglow consistent with the XRT position (Osborne et al., 
GCN Circ. 13042) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

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

white_FC          3072         3222          147         >21.4
white             3072        16503         2114         >22.8
v                 3228        21300         2013         >20.3
b                 4048        15591         1233         >20.7
u                 3843         5479          393         >19.7
w1                3638        22969         1136         >20.9
m2                3433        22206         1082         >20.8
w2                4460        17192         1754         >21.9

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.52 in the direction of the 
burst (Schlegel et al. 1998).