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IAUC 8108: 2003da, 2003db; GRB 030329

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                                                  Circular No. 8108
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
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SUPERNOVAE 2003da AND 2003db
     Additional apparent supernovae found by T. Boles (cf. IAUC

SN      2003 UT      R.A.  (2000.0)  Decl.    Mag.      Offset
2003da  Apr.  6.90   9 23 47.56  +42 10 48.6  15.9   1".8 W, 12".0 S
2003db  Apr.  7.00   9 36 58.83  +31 20 01.7  17.5   8".8 E, 9".4 N

Additional unfiltered CCD magnitudes from Boles' images:  SN 2003da
in UGC 4992, Feb. 2, [19.0; Mar. 2, [19.0?; Apr. 7.83, 15.9.  SN
2003db in MCG +05-23-21, Feb. 22, [19.0; Apr. 7.84, 17.5.  Neither
object is present on Palomar Sky Survey red or blue plates.

GRB 030329
     P. Garnavich, University of Notre Dame; T. Matheson, Harvard-
Smithsonian Center for Astrophysics (CfA); D. Eisenstein,
University of Arizona (UA); B. Pindor, Princeton University; N.
Hathi, R. Jansen, R. Windhorst, and L. Echevarria, Arizona State
University; J. Lee (UA); K. Krisciunas, Observatories of the
Carnegie Institution of Washington (OCIW) and Cerro Tololo
Interamerican Observatory; P. Martini, OCIW; and W. Brown, N.
Caldwell, P. Berlind, M. Calkins, and K. Z. Stanek (CfA) report
that spectra of the afterglow of GRB 030329 (IAUC 8101) have been
obtained with the 6.5-m MMT, 6.5-m Magellan, and 1.5-m Tillinghast
telescopes regularly from Mar. 30.12 to Apr. 7.25 UT.  The early
spectra consist of a power-law continuum with narrow emission
lines originating from H II regions in the host galaxy at a
redshift of z = 0.168.  However, the spectra taken on Apr. 6 (and
confirmed on Apr. 7) now show broad peaks in flux that are
characteristic of a supernova.  The broad bumps are seen at
approximately 570 and 480 nm, and these are similar to those in the
spectrum of the peculiar type-Ic supernova 1998bw a week before
maximum light (Patat et al. 2001, Ap.J. 555, 900).  SN 1998bw was
associated with GRB 980425 (IAUC 6884, 6895, 6896, 6899, 6901,
6903; Galama et al. 1998, Nature 395, 670) but the energy of that
burst was 100 times less than that of classical gamma-ray-bursts
(GRBs).  The fading power-law spectrum suggests the presence of
non-thermal emission, while broad features in the recent spectrum
are a signature of atomic absorption from high velocity gas that is
indicative of a supernova.  The spectral similarity to SN 1998bw
and other 'hypernovae' such as 1997ef (IAUC 6783, 6798, 6820;
Iwamoto et al. 2000, Ap.J. 534, 660) provides strong evidence that
at least some classical GRBs originate from core-collapse

                      (C) Copyright 2003 CBAT
2003 April 7                   (8108)            Daniel W. E. Green

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