GCN Circular 28177
Subject
GRB 200729A: Swift/UVOT Upper Limits
Date
2020-07-30T12:41:58Z (4 years ago)
From
Samantha Oates at MSSL <samantha.oates@alumni.ucl.ac.uk>
S. R. Oates (U.Birmingham) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200729A
145 s after the BAT trigger (Evans et al., GCN Circ. 28165).
No optical afterglow is detected above the flux of NGC 4242, consistent with the XRT position
(Osborne et al. GCN Circ. 28168), in the initial UVOT exposures. For all filters, we
have attempted to subtract off the light of NGC 4242 by measuring the flux
at a position offset from the XRT position, but of a similar brightness.
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 145 295 147 >20.0
u_FC 303 553 246 >18.9
white 145 1874 431 >20.0
v 633 1749 136 >17.6
b 559 1849 136 >18.7
u 303 1824 362 >18.9
w1 682 1799 97 >18.2
m2 658 1428 39 >17.8
w2 1359 1725 58 >17.8
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).