GCN Circular 9174
Subject
GRB 090417B: Swift/UVOT Upper Limits
Date
2009-04-20T19:46:26Z (15 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/GSFC/USRA) and B. Sbarufatti (INAF-IASFPA)
report on the behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 090417B starting 378 s
after the BAT trigger (Sbarufatti, et al., 2009, GCN Circ. 9135).
Settled exposures started at T+395 s. We do not find any new source,
relative to the DSS, USNO-B1.0, or 2MASS at the position of the XRT
afterglow (Sbarufatti, et al. 2009, GCN Circ. 9155). Preliminary
3-sigma upper limits for detecting a source in the white finding
chart, and the co-added images, using a 2.5 arcsecond radius circular
aperture, are
Filter T_start T_stop Exp(s) Mag
--------------------------------------------
white (fc) 395 545 147 >21.7
v 552 13,098 1237 >21.3
b 651 19,457 862 >21.9
u 1300 25,241 1376 >22.0
uvw1 601 25,174 2300 >22.2
uvm2 750 24,268 1878 >21.8
uvw2 700 29,604 1331 >22.0
white 395 7823 841 >22.6
--------------------------------------------
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} = 0.02 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).