GCN Circular 22992

Subject

GRB 180720C: Swift/UVOT Upper Limits

Event

Date

2018-07-21T08:35:26Z (7 years ago)

From

Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>

S. R. Oates (U. Warwick) and S. J. LaPorte (PSU) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180720C
100 s after the BAT trigger (LaPorte et al., GCN Circ. 22982Loading...
 
 ).
No optical afterglow consistent with the XRT position (Evans et al., GCN
Circ. 22987Loading...
 
 ) 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)         100         250          147           >20.3
white              100         5490         541           >21.0    
u (FC)             312         425          111           >19.2
u                  312         11199       1193           >20.6
v                  4263        5901         393           >19.1
b                  3646        11902       1072           >20.8
uvw1               4674        10285       1133           >20.3
uvm2               4469        6106         393           >19.7
uvw2               4058        5696         393           >19.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the significant reddening of E(B-V) = 2.11 in the direction of the burst
(Schlegel et al. 1998).