[vsnet-grb-info 7628] GRB 090418A: Swift/UVOT Detection of the Neighbouring Galaxy
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Wed Apr 22 06:53:04 JST 2009
TITLE: GCN CIRCULAR
NUMBER: 9183
SUBJECT: GRB 090418A: Swift/UVOT Detection of the Neighbouring Galaxy
DATE: 09/04/21 21:52:49 GMT
FROM: Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland at nasa.gov>
S. T. Holland (CRESST/GSFC/USRA) reports on the behalf of the Swift
UVOT team:
Swift/UVOT observed the POSS2 galaxy (Pavlenko, et al., 2009,
GCNC 9179) located approximately 4 arcsec northwest of the afterglow
of GRB 090418A (Mangano, et al.,2009, GCNC 9149). We obtain the
following preliminary magnitudes and 1-sigma errors for this galaxy.
Filter Exposure Mag Err Sigma
-------------------------------------
v 6163 21.0 0.2 5.5
b 4361 22.2 0.5 2.3
u 6057 21.3 0.2 5.6
uvw1 6178 21.6 0.2 4.7
uvm2 2109 21.5 0.4 2.9
uvw2 1357 21.3 0.3 3.4
-------------------------------------
Exposure is the total exposure time in seconds. The quoted magnitudes
have not been corrected for the expected Galactic extinction along
the line of sight corresponding to a reddening of E_{B-V} = 0.04 mag
(Schlegel, et al., 1998, ApJS, 500, 525). All photometry is on the
UVOT photometric system described in Poole et al. (2008, MNRAS, 383,
627).
The detection of the galaxy in the uvw2 filter suggests that the
galaxy has a redshift of less than approximately 1.3. The redshift of
the afterglow is at least z = 1.608 (Chornock, et al., 2009, GCNC
9151). Therefore, we conclude that this galaxy is unlikely to be the
host galaxy of GRB 090418A, in agreement with Pavlenko, et al. (2009,
GCNC 9179).
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