GCN Circular 9969
Subject
GRB 090929B: Swift/UVOT Observations
Date
2009-09-29T19:13:57Z (15 years ago)
From
Peter Curran at MSSL <pac@mssl.ucl.ac.uk>
P.A. Curran (MSSL-UCL), F. Marshall (GSFC), S. Holland (GSFC) and C.
Pagani (PSU) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 090929B 94s
after the BAT trigger (Pagani et al., GCN Circ. 9963). No optical
afterglow is detected in the b, u or uvw2 UVOT exposures. There is a
detection in the white filter, consistent with the enhanced XRT position
(Goad et al. GCN 9964, Page et al. GCN 9965), the proposed optical
counterpart (Wren et al. GCN 9967) and a USNO catalogued star (R2=19.3).
Since the photometry is contaminated by a bright (R = 9.5), near-by star,
we cannot determine the nature of the source at this time.
Preliminary magnitudes and 3-sigma upper limits using the UVOT photometric
system (Poole et al. 2008, MNRAS, 383, 627) for the initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
----------------------------------------------------------------
white 94 4032 292 18.7 +/- 0.5
b 3627 3827 197 >20.5
u 3422 3622 197 >20.3
uvw2 4038 4224 183 >20.3
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.07 in the direction of the burst
(Schlegel et al. 1998).