GCN Circular 21399
Subject
GRB 170728B: Swift/UVOT Further Analysis
Event
Date
2017-07-31T19:31:50Z (9 years ago)
From
Sam LaPorte at PSU <sjl5346@psu.edu>
GRB 170728B: Swift/UVOT Detection
S. J. LaPorte (PSU), S.W.K. Emery (MSSL), and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:
After detailed analysis of initial data reported in LaPorte and Cenko,
GCN Circ. 21388, we do find a significant detection in initial optical
filter exposures.
The Swift/UVOT began settled observations of the field of GRB 170728B
473 s after the BAT trigger (Cenko et al., GCN Circ. 21371).
A fading source consistent with the optical position
(D'Avanzo et al. GCN Circ. 21373)
is detected in the initial UVOT exposures.
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 876 1026 147 20.56 +/- 0.20
v 630 8278 627 20.23 +/- 0.27
b 728 2561 194 20.60 +/- 0.29
u 703 13868 1276 >21.2
w1 679 19251 2000 >21.6
m2 6847 18681 1279 >22.1
w2 6437 8073 393 >21.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).