TITLE:   GCN CIRCULAR
NUMBER:  19308
SUBJECT: GRB 160412A: Swift/UVOT Upper Limits
DATE:    16/04/12 21:09:39 GMT
FROM:    Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and S. L. Gibson (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160412A
90 s after the BAT trigger (Gibson et al., GCN Circ. 19298).
No optical afterglow consistent with the enhanced XRT position
(Goad et al. GCN Circ. 19299)
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            90          240          147         >20.4
u_FC               303          552          246         >19.1
white               90         1878          431         >21.1
v                  633         2101          175         >19.3
b                  558         2026          156         >19.7
u                  303         2001          362         >19.5
w1                 682         2150          156         >19.8
m2                1063         2125           97         >19.2
w2                 608         2076          175         >19.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).