GCN Circular 33266
Subject
GRB 230204A: Swift/UVOT Upper Limits
Date
2023-02-04T23:36:26Z (a year ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
S. J. LaPorte (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230204A
156 s after the BAT trigger (D'Ai et al., GCN Circ. 33260).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 33261)
is detected in the initial UVOT exposures.
A known source with no significant signs of fading
is detected 2.88 arcsec from the XRT position at:
RA (J2000): 15h 52m 47.83s
Dec (J2000): -50d 54' 56.74"
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 156 306 147 >17.5
u_FC 314 564 246 >19.1
white 156 1372 373 >17.8
v 645 1596 117 >15.9
b 570 1521 97 >17.9
u 314 5553 382 >19.1
w1 695 5489 274 >19.1
m2 670 1446 97 >18.8
w2 621 1571 117 >18.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 2.516 in the direction of the burst
(Schlegel et al. 1998).