GCN Circular 9203
Subject
GRB 090422: Swift/UVOT Upper Limits
Date
2009-04-23T11:37:54Z (15 years ago)
From
Alice Breeveld at MSSL-UCL <aab@mssl.ucl.ac.uk>
A. A. Breeveld (MSSL/UCL) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 090422 starting 55 s
after the BAT trigger (Ukwatta, et al., 2009, GCN Circ. 9185). Settled
exposures started at T+74 s with a Finding Chart (FC) in the white
filter. We do not find any new source, at the enhanced position of the
XRT afterglow (Beardmore, et al. 2009, GCN Circ. 9194) nor at the
position of the candidate found by the Liverpool Telescope (Guidorzi,
et al. 2009, GCN Circ. 9197). 3-sigma upper limits for detecting a
source in the white and u FCs, and subsequent co-added images in all
filters are:
Filter T_start T_stop Exp(s) Mag
----------------------------------------------------------
white (FC) 74 224 147 >20.5
u (FC) 287 537 246 >19.6
v 617 11744 1317 >20.3
b 542 18318 1145 >20.8
u 690 24099 2059 >20.8
uvw1 666 23300 2203 >21.0
uvm2 641 22393 2092 >20.8
uvw2 592 10831 1318 >20.8
white 566 5591 341.4 >20.8
---------------------------------------------------------
The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight corresponding to a
reddening of E_{B-V} = 0.198 mag (Schlegel, et al., 1998, ApJS, 500,
525). All photometry is on the UVOT photometry system described in
Poole et al. (2008, MNRAS, 383, 627).