TITLE:   GCN CIRCULAR
NUMBER:  1599
SUBJECT: GRB 021004, spectroscopic observations
DATE:    02/10/07 20:50:05 GMT
FROM:    Peter Garnavich at U of Notre Dame  <pgarnavi@miranda.phys.nd.edu>

F. Javier Castander (IEEC-Barcelona/U. de Chile), E. Gawiser (Yale/U. de Chile),
C. Foltz, S. West (MMTO), G. Williams (MMTO/SAO), E. Falco (FLWO), 
T. Matheson, K.Z. Stanek (CfA), P. Garnavich (Notre Dame) and L. Macri (NOAO)
report:

Spectra of the GRB 021004 afterglow were obtained with the
Magellan 6.5m Baade Telescope on Oct. 5.0 UT and with the
MMT on Oct. 5.1, 5.3 and 6.3 UT. The spectra confirm two major MgII
absorption systems at z=1.38 and z=1.60 (GCN 1569, 1579, 1582). The moderate
resolution Magellan spectra show that the strong, unidentified line
at 515 nm is made of 3 components separated by 0.9 nm. The MMT spectra
extended to 330 nm and show no Lyman forest break implying a
limit to the redshift of z<1.7. 

The CIV absorption in the z=1.60 system is very strong with an
equivalent width of 0.5 nm (rest frame). There is another strong
line 2000 km/s to the blue of the CIV which may be  a second CIV
component. In addition, an emission line is detected at 405.2 nm forming
a P-Cygni profile with the CIV absorption. We conclude that the host
is a starburst galaxy.

This message may be cited.