GCN Circular 6444
Subject
GRB 070521: Subaru observations and possible host detection
Date
2007-05-21T23:46:59Z (17 years ago)
From
Nobuyuki Kawai at Tokyo Tech <nkawai@hp.phys.titech.ac.jp>
T. Hattori, K. Aoki (Subaru Telescope, NAOJ), and N. Kawai
(Tokyo Tech) report on behalf of the Subaru GRB team:
"We observed the field of GRB 070521 (Guidorzi et al., GCN 6431)
with FOCAS on the Subaru Telescope starting at 07:31(UT) (40 min after
the trigger) with total exposures of 1920 sec (120s x 16) in z'-band
and 360 sec (120s x 3) in i'-band.
We detected a faint source inside the XRT error circle at
RA=16:10:38.55, DEC=30:15:27.7
with a positional uncertainty of 0.5"
and an approximate magnitude of z' ~ 23.5.
We obtained 3600 sec long-slit spectra of this faint source
covering a wavelength range from 6000 to 10000 Ang.
We detected [O III] 5007, 4959 emission lines at z=0.553.
If this object is the host galaxy of GRB 070521, its location at a
relatively low redshift makes it a good candidate for searching the
supernova component. Note, however, that the absence of a bright
afterglow may indicate that the GRB source is embedded in a region
with high extinction, or the host identification is spurious.
The image may be viewed at
http://www.hp.phys.titech.ac.jp/nkawai/grb/070521/.
We thank the Subaru Observatory for the support of this observation."