GCN Circular 33392

Subject

GRB 230228A: Swift/UVOT Upper Limits

Event

Date

2023-03-02T10:15:52Z (3 years ago)

From

Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and S. Dichiara (PSU) report on behalf of the 
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230228A 
122 s after the BAT trigger (Dichiara et al., GCN Circ. 33378Loading...
 
 ).
No optical afterglow consistent with the enhanced XRT position 
(Beardmore et al., GCN Circ. 33382Loading...
 
 ) 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           122          272          147         >20.2
u_FC               335          585          246         >19.5
white              122         1706          240         >20.6
v                  665         1752           97         >18.8
b                  591         1851           88         >19.8
u                  335         1830          341         >19.7
w1                 714         1806          117         >20.0
m2                 689         1780           97         >19.7
w2                 640         1731           78         >20.1

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.085 in the direction of 
the burst (Schlegel et al. 1998).