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GCN Circular 1152

Subject
GRB011121: possible redshift, continued decay
Date
2001-11-22T12:10:45Z (22 years ago)
From
Krzysztof Z. Stanek at CfA <kstanek@cfa.harvard.edu>
L. Infante (Pontificia Univ. Catolica de Chile), P. M. Garnavich
(Notre Dame), K. Z. Stanek (Harvard-Smithsonian CfA) and Lukasz
Wyrzykowski (Warsaw University Observatory) report:

Spectra of the possible OT (Wyrzykowski et al.: GCN 1150) obtained
with the Magellan Walter Baade 6.5m telescope and the LDSS-2
spectrograph on Nov. 22.3 (UT) show a smooth continuum with a peak
flux near 650 nm. Narrow emission lines, likely from the host galaxy,
are seen at 507.58 nm and 681.0 nm, which may correspond to [O II]
372.7 and [O III] 500.7 nm at a redshift of 0.36. The depressed blue
end of the spectrum is most likely due to strong Galactic dust
extinction.

Also, additional R-band observation of the GRB011121 field carried out
with the OGLE 1.3m telescope 13.75 hours after the burst indicates
continuing fading behavior of the afterglow, as seen already by Stanek
et al. (GCN 1151):

HJD-2450000         UT           R_c       exp
2235.85176    011122 08:30  18.80+-0.03  600 sec

This behavior is consistent with a power-law decay with an index of
-1.65. The R-band magnitudes are relative to star "A" of Wyrzykowski
et al. (see finding chart at
http://cfa-www.harvard.edu/cfa/oir/Research/GRB/).

The faint object 0.5" to the northeast of the OT reported by Stanek et
al. is easily visible in 600 sec R-band exposure.

Relatively low redshift and fast decay of its afterglow make GRB011121
an attractive search target for a possible supernova associated with
this burst.

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