Central Bureau for Astronomical Telegrams
IAUC 8051: 2002kg; 2002hz
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Circular No. 8051
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2002kg IN NGC 2403
Further to IAUC 8048, M. Schwartz and W. Li report the LOTOSS
discovery of a supernova on unfiltered images taken with the
Tenagra II telescope and KAIT. The object was at mag 19 +/- 0.3,
and possibly showed a brightening trend, from 2002 Oct. 26 to 2003
Jan. 1 UT; SN 2002kg is present in Tenagra II images taken on 2002
Oct. 30, Nov. 14, 22, 24, 25, Dec. 8, and 2003 Jan. 1, and in KAIT
images taken on 2002 Oct. 26, Nov. 1, and Dec. 2. The object is
located at R.A. = 7h37m01s.83, Decl. = +65o34'29".3 (equinox
2000.0), which is 71".7 east and 96".0 south of the nucleus of NGC
2403. A KAIT image of the same field taken on 1998 Nov. 13 showed
nothing at this position (limiting mag about 19.5). A. V.
Filippenko and R. Chornock, University of California, Berkeley,
write: "Inspection of CCD spectra (range 310-1000 nm) obtained on
Jan. 6 UT with the Keck I 10-m telescope (+ LRIS) shows that SN
2002kg is of type IIn, specifically the variety similar to SN
1997bs (Van Dyk et al. 2000, PASP 112, 1532). The narrow Balmer
emission lines (unresolved; FWHM < 500 km/s) have a broader base
with FWHM roughly 2500 km/s (measured from H-beta), and there is
weak Fe II emission at 450-460 and 515-535 nm. Prominent,
unresolved [N II] 654.8- and 658.4-nm emission lines are visible,
yet other forbidden lines are weak or absent, suggesting a possible
nitrogen overabundance in the circumstellar gas. Similar recent
examples of such objects (but without the [N II] emission) include
SN 1999bw (IAUC 7152), SN 2000ch (IAUC 7421), and SN 2001ac (IAUC
7597). We have previously argued that they might not be genuine
supernovae, but rather superoutbursts of luminous variable stars
(e.g., Filippenko et al. 1995, A.J. 110, 2261; Van Dyk et al. 2000,
PASP 112, 1532). SN 2002kg provides strong evidence for this
hypothesis; at a distance modulus of 27.6 mag (Freedman and Madore
1988, Ap.J. 332, L63), its absolute magnitude is only about -9.
However, these objects are still classified as supernovae, at least
until they are convincingly shown not to be stellar explosions."
SUPERNOVA 2002hz IN UGC 12044
Filippenko and Chornock add that inspection of CCD spectra,
obtained as above on Jan. 7 UT, shows that SN 2002hz (IAUC 8017) is
of type Ib, roughly 2 months past maximum brightness and starting
to enter the nebular phase. He I lines are clearly present,
although their strength is in most cases difficult to judge owing
to blending with other lines.
(C) Copyright 2003 CBAT
2003 January 15 (8051) Daniel W. E. Green
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