GCN Circular 9234
Subject
Swift/UVOT observations of GRB 090424
Date
2009-04-24T21:42:37Z (16 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
P.Schady (MSSL/UCL) and J. K. Cannizzo (NASA/UMBC) report on behalf of the
Swift/UVOT team:
The Swift/UVOT started settled observations of the burst GRB090424
(Cannizzo et al. GCN Circ. 9223) with the finding chart (fc) exposure in
white, 167s after the BAT trigger. The afterglow is detected in the all
filters at the position reported by Cannizzo et al. (GCN Circ. 9223),
placing an upper limit on the redshift of ~1.3. The combined UVOT data
indicates that the afterglow is fading with a decay index of alpha ~ 0.9.
The UVOT magnitudes our reported below:
Filter Tmid(s) Exp(s) Magnitude
white (fc) 167 147.4 15.27 +/- 0.01
u (fc) 429 245.8 16.40 +/- 0.03
white 594 19.4 16.99 +/- 0.07
v 644 19.5 16.86 +/- 0.19
b 570 19.5 17.27 +/- 0.13
u 1122 19.5 17.44 +/- 0.20
uvw1 695 19.5 16.81 +/- 0.19
uvm2 670 19.4 17.39 +/- 0.34
uvw2 793 19.4 17.51 +/- 0.27
The values quoted above are in the UVOT photometric system (Poole et al.
2008, MNRAS, 383, 627) and are not corrected for the expected Galactic
extinction corresponding to a reddening of E(B-V)=0.025 mag in the
direction of the burst (Schlegel et al. 1998).