GCN Circular 21913
Subject
GRB 170921A: Swift/UVOT Upper Limits
Event
Date
2017-09-22T14:56:56Z (8 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 170921A: Swift/UVOT Upper Limits
S. J. LaPorte (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
(Beardmore et al. GCN Circ. 21906)
The Swift/UVOT began settled observations of the field of GRB 170921A
101 s after the BAT trigger (D'Ai et al., GCN Circ. 21901).
No optical afterglow consistent with the XRT position
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 101 251 147 >20.7
u_FC 259 509 246 >20.4
white 101 6816 766 >21.4
v 590 7186 451 >19.9
b 516 6611 471 >20.6
u 259 12926 1346 >21.1
w1 639 12273 1171 >20.6
m2 1412 11366 1102 >21.0
w2 566 16512 687 >21.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).