GCN Circular 9877
Subject
GRB 090902B: Swift/UVOT refined analysis
Date
2009-09-03T19:55:45Z (15 years ago)
From
Craig Swenson at PSU/Swift <cswenson@astro.psu.edu>
C. A. Swenson (PSU) and G. Stratta (ASDC) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began observations of the field of GRB 090902B
approximately 12.5 hours after the Fermi GBM/LAT trigger (de Palma
et al., GCN Circ. 9867; Bissaldi et al., GCN Circ. 9866). We can
now confirm the detection of the optical afterglow (Swenson et al.,
GCN Circ. 9869; Perley et al., GCN Circ. 9870; Cucchiara et al.,
GCN Circ. 9873; Olivares et al., GCN Circ. 9874; Guidorzi et al.,
GCN Circ. 9875) coincident with the enhanced Swift-XRT position (Evans,
GCN Circ. 9871). We also observe a decay in the optical afterglow.
The observed magnitudes using the UVOT photometric system (Poole et
al. 2008, MNRAS, 383, 627) are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u 45096 46188 1075 20.26 � 0.19
u 50891 58703 3613 20.50 � 0.11
u 62457 81106 8756 20.85 � 0.10
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).