GCN Circular 22605
Subject
GRB 180404A: Swift/UVOT Detection
Event
Date
2018-04-05T17:04:53Z (8 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180404A
90 s after the BAT trigger (Gropp et al., GCN Circ. 22589).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 22592)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 05:34:11.64 = 83.54850 (deg.)
Dec (J2000) = -37:10:03.9 = -37.16774 (deg.)
with an estimated uncertainty of 0.50 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) 90 240 147 19.47 +/- 0.09
white 90 770 180 19.34 +/ -0.10
white 45830 52026 1028 >21.66
v 632 5179 99 >18.9
b 558 750 39 >19.4
u (fc) 302 552 246 18.95 +/- 0.12
u 303 726 265 18.95 +/ -0.14
w1 682 701 19 >17.8
m2 656 676 19 >17.4
w2 607 5094 216 19.45 +/- 0.28
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).