GCN Circular 22611
Subject
GRB 180404B: Swift/UVOT Detection
Date
2018-04-06T18:14:06Z (7 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) and S. J. LaPorte (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180404B
82 s after the BAT trigger (LaPorte et al., GCN Circ. 22590).
A fading source consistent with the XRT position
(Beardmore et al. GCN Circ. 22594)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 03:33:34.23 = 53.39262 (deg.)
Dec (J2000) = -50:12:54.2 = -50.21506 (deg.)
with an estimated uncertainty of 0.46 arc sec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white (fc) 82 231 147 18.66 +/- 0.09
white 82 1720 411 19.39 +/- 0.09
white 6421 6620 196 >20.7
v 624 7031 510 >19.5
b 550 7661 322 >20.3
u (fc) 295 545 245 19.49 +/- 0.31
u 295 1670 343 19.70 +/- 0.29
u 6011 7648 393 >20.1
w1 674 7442 510 >20.6
m2 1600 7236 413 >20.5
w2 600 6826 452 >20.2
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).