GCN Circular 21847
Subject
GRB 170906A: Swift/UVOT Detection
Event
Date
2017-09-07T18:30:36Z (8 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170906A
77 s after the BAT trigger (Siegel et al., GCN Circ. 21821).
A source consistent with the XRT position (Siegel et al. GCN Circ. 21821)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 13:35:49.20 = 203.95501 (deg.)
Dec (J2000) = -47:06:02.1 = -47.10057 (deg.)
with an estimated uncertainty of 0.42 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 listed
below. The afterglow appears to have brightened during the early observations and
faded by later orbits, confirming the analysis of Lipunov et al. (GCN Circ. 21830).
Filter T_start(s) T_stop(s) Exp(s) Mag
white (fc) 77 227 147 16.41 +/- 0.03
white 570 590 19 15.47 +/- 0.04
white 744 764 19 15.65 +/- 0.05
v 620 639 19 14.65 +/- 0.07
v 11125 23192 901 >19.82
b 545 565 20 15.59 +/- 0.06
b 12629 12744 112 >19.63
u 290 539 246 15.47 +/- 0.03
u 694 714 19 15.47 +/- 0.08
u 17786 18086 295 >19.82
uvm2 15973 16873 885 >20.09
uvw1 669 689 19 17.00 +/- 0.24
uvw1 16880 17780 885 >20.23
uvw2 595 615 19 >17.0
uvw2 10219 22561 1771 >20.61
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).