Central Bureau for Astronomical Telegrams
IAUC 6830: 1998T; 1998S; V854 Cen
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Circular No. 6830
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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SUPERNOVA 1998T IN IC 694
W.-d. Li, University of California at Berkeley (UCB), forwards
the report from C. Li that Zhou Wan has found an apparent supernova
(unfiltered CCD mag 15.4) on Mar. 3 UT as part of the Beijing
Astronomical Observatory Supernova Survey. As with SN 1998S (cf.
IAUC 6829), this object was confirmed by the Lick Supernova Survey
at unfiltered mag about 14.5 on Mar. 4.3, with the corresponding
KAIT position given as R.A. = 11h28m32s, Decl. = +58o33'.7 (equinox
2000.0); SN 1998T appears in a dust lane of the irregular host
galaxy that has no apparent nucleus, so the relative offsets cannot
be accurately determined, and its close proximity to a knot makes
it difficult to measure (the magnitudes were derived from
subtracted images). Observations of the same field prior to Mar. 3
do not show an object at the position of SN 1998T.
A. V. Filippenko and E. C. Moran, UCB, report that on Mar. 5
they obtained a Keck-2 spectrogram (range 510--900 nm, resolution 1
nm) of the stellar-looking knot on the southern side of the dust
lane of IC 694 (the eastern part of the irregular galaxy Arp 299 =
Markarian 171, of which the western part is NGC 3690; see
Wynn-Williams et al. 1991, Ap.J. 377, 426). SN 1998T is indeed a
supernova, of type Ib; strong P-Cyg profiles of He I lines are
visible. Narrow nebular emission lines are very intense.
SUPERNOVA 1998S IN NGC 3877
Filippenko and Moran also report: "A low-resolution Keck-2
spectrum, obtained as above, shows that the type-II SN 1998S (cf.
IAUC 6829) is peculiar; the spectrum contains prominent H and He
emission lines superposed on a featureless blue continuum. In many
respects, the spectrum resembles that of the type-IIn SN 1997eg
(cf. IAUC 6794): the lines have multiple components, including a
very narrow (unresolved) one that is probably produced by flash-
ionized circumstellar gas. This object might become very luminous
at radio and x-ray wavelengths, due to strong interaction between
the ejecta and circumstellar material."
V854 CENTAURI
This R CrB-type variable is fading, as indicated by the
following visual magnitude estimates, in part from the AAVSO: Feb.
4.67 UT, 7.6 (F. Farrell, Christies Beach, Australia); 21.9, 8.4
(B. Monard, Pretoria, South Africa); 25.22, 8.3 (A. Pereira, Cabo
da Roca, Portugal); 26.96, 8.7 (Monard); Mar. 1.20, 9.1 (Pereira);
2.92, 9.0 (Monard); 3.85, 8.9 (Monard).
(C) Copyright 1998 CBAT
1998 March 5 (6830) Daniel W. E. Green
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