GCN Circular 25570
Subject
GRB 190829A: Swift/UVOT detection of an optical afterglow with a rise
Date
2019-08-30T10:42:30Z (5 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (U.Warwick) and S. Dichiara (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 190829A
106 s after the BAT trigger (Dichiara et al., GCN Circ. 25552).
An optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 25567) and the optical afterglow reported by
Dabancheng-0.5m (Xu et al. GCN Circ. 25555), MASTER-net
(Lipunov et al. GCN Circ. 25558), GROWTH (Kumar et al. GCN Circ. 25560),
NOT (Heintz et al. GCN Circ. 25563), GTC (Valeev et al. GCN Circ. 25565)
and GROND (Chen et al. GCN Circ. 25569) is detected in the initial UVOT exposures.
An inital rise is observed in the UVOT images peaking at ~1400s. The afterglow
is detected in white, v, b, u and w1, but is not detected in the initial m2 and w2 exposures.
For m2 and w2 we provide upper limits from a summed image created from 4 individual
exposures closest to the peak.
Preliminary detections and 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 other early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 106 256 147 20.05 +/- 0.17
u_FC 264 514 246 19.95 +/- 0.27
white 546 566 19 19.48 +/- 0.30
v 771 791 19 17.52 +/- 0.28
b 1149 1168 19 17.29 +/- 0.15
u 845 865 19 18.40 +/- 0.36
w1 1099 1638 78 18.54 +/- 0.35
m2 1075 1614 78 > 18.5
w2 1026 1565 78 > 18.7
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998). In addition, the underlying host galaxy has not
been subtracted.