TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2120
SUBJECT: GRB 030329: Supernova Confirmed
DATE:    03/04/08 20:13:40 GMT
FROM:    Krzysztof Z. Stanek at CfA  <kstanek@cfa.harvard.edu>

T. Matheson (CfA), P. Garnavich (Notre Dame), E. W. Olszewski
(Steward), P. Harding (Case Western), D. Eisenstein (Arizona),
B. Pindor (Princeton), N. Hathi, R. Jansen, R. Windhorst,
L. Echevarria (ASU), J. Lee (Arizona), W. Brown, N. Caldwell,
P. Berlind, M. Calkins and K. Z. Stanek (CfA) report:


Additional spectra of the afterglow of GRB 030329 (Peterson & Price,
GCN 1985; Torii: GCN 1986) were obtained with the 6.5-m MMT on
Apr. 8.13 UT. The spectral features discovered by Matheson et al. (GCN
2107) and confirmed by Garnavich et al. (IUAC 8108) continue to
develop. Subtracting a scaled version of the Apr. 4.27 UT power-law
spectrum from the Apr. 8.13 spectrum reveals an energy distribution
remarkably similar to that of the SN1998bw a week before maximum light
(Patat et al. 2001, ApJ, 555, 900). This spectrum can be seen at

http://cfa-www.harvard.edu/~tmatheson/compgrb.jpg

The spectral similarity to SN 1998bw and other 'hypernovae' such as
1997ef (Iwamoto et al. 2000, ApJ, 534, 660) provides strong evidence
that classical GRBs originate from core-collapse supernovae.

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