GCN Circular 29
Subject
Untitled
Date
1970-01-01T00:00:00Z (55 years ago)
From
circulars@gcn.nasa.gov
GRB 971214 Optical Observations #029
S. R. Kulkarni, K. L. Adelberger, J. S. Bloom, T. Kundic, L. Lubin,
California Institute of Technology, report:
"On December 28, 1997, Kundic and Lubin obtained spectra of the optical
transient of GRB 971214 (IAUC 6788) with the Low Resolution Imaging
Spectrograph (LRIS) mounted on the Keck II telescope. The seeing
conditions were excellent. If the transient continued the power-law
decay as indicated by the data from Halpern et al. IAUC 6788) then by
this epoch the light at this position should be dominated by the host
(cf. Kulkarni et al. GCN #27; ATEL #5). Analysis of these spectra show
a slightly extended emission feature at 5384 A. Additionally, a broad
absorption feature is seen at 5752 A. We cannot at this time make a
definitive statement about the redshift of the host. If, the emission
feature is identified as Lyman-alpha and the absorption feature as OI
1302 A then the redshift of the (presumed) host is z=3.43. However,
there appears to be no obvious depression bluewards of this feature as
is normally seen in high-redshift objects (caused by the Lyman
forest). If, however, the emission feature is identified with the
[OII] 3727 line then the redshift is z=0.44.
A strong emission feature at a wavelength of 5602 A is also seen in the
spectrum of the nearby galaxy G1 (GCN #12; GCN #13). Identifying this as
the [OII] 3727 A feature as well as matching major absorption features
yields a redshift of z=0.50.
We are in the process of analyzing additional LRIS data to improve the
signal-to-noise ratio and also to understand the apparent discrepancy
with similar data obtained on 17 Dec 1997 UT (GCN #12). We note that
the earlier data were obtained under bright lunar conditions while the
data reported herein was obtained during dark time.
This message is citable."