[vsnet-grb-info 14892] GRB 140428A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16187
SUBJECT: GRB 140428A: Swift/UVOT Upper Limits
DATE:    14/04/29 21:13:07 GMT
FROM:    Frank Marshall at GSFC  <femarsha at khamseen.gsfc.nasa.gov>

F. E. Marshall (NASA/GSFC) and D. Kocevski (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 140428A
104 s after the BAT trigger (Kocevski et al., GCN Circ. 16177).
No optical afterglow consistent with the optical position
(Perley, GCN_Circ. 16180) 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 initial exposures are:

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

white              104          254          147         >21.2
v                 5454         5653          197         >20.3
b                 4838         5039          197         >21.4
u                  264          271            7         >19.5
uw1               5864         6030          197         >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.009 in the direction of the burst
(Schlegel et al. 1998).