GCN Circular 25978
Subject
GRB 191004B: Swift/UVOT Detection
Event
Date
2019-10-07T20:45:09Z (7 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 191004B: Swift/UVOT Detection
S. J. LaPorte (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 191004B
69 s after the BAT trigger (Cenko et al., GCN Circ. 25947).
A fading source consistent with the XRT position
(Beardmore et al. GCN Circ. 25951)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 03:16:49.10 = 49.20459 (deg.)
Dec (J2000) = -39:38:03.9 = -39.63441 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence),
consistent with the positions reported by LCO (Strausbaugh et al. GCN Circ.
25949),
NOT (Heintz et al. GCN Circ. 25954), VLT/X-Shooter (D'Elia et al. GCN Circ.
25956),
COATLI (Watson et al. GCN Circ. 25958), and GROND (Schady et al. GCN Circ.
25960).
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
b 38697 38997 295 >20.42
uvm2 44827 45727 885 >20.25
u 294 387 91 >19.04
v 43916 44822 885 >20.07
uvw1 45734 46281 538 >19.96
uvw2 39915 40544 618 >20.09
white 82 232 147
18.01+-0.05
white 39003 39909 885 20.51+-0.13
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).