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IAUC 6832: 1998S; V1333 Aql; 1997dq

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                                                 Circular No. 6832
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
Phone 617-495-7244/7440/7444 (for emergency use only)

     P. Garnavich, S. Jha, and R. Kirshner, Harvard-Smithsonian
Center for Astrophysics, report:  "A spectrum taken by J. Huchra
with the 1.5-m Tillinghast telescope on Mar. 5.3 UT confirms that
SN 1998S is a narrow-lined type-II supernova (type IIn; cf. IAUC
6830) but shows it to be quite unusual.  There are Balmer emission
lines with narrow peaks and broad wings superimposed on a very blue
continuum.  The full width at the base of H-alpha is 8200 km/s.
What makes this type-IIn object stand out are the strengths of He
II 468.6-nm and permitted N III/C III 464-nm, which are comparable
to the flux of H-beta.  These features are identical those seen in
SN 1983K (Niemela et al. 1985, A.J. 289, 52), which was discovered
two weeks before maximum light.  There are also weaker He II lines
seen at 541.1 and 569.5 nm.  A broad emission feature peaking at
580.0 nm may be C IV, characteristic of Wolf-Rayet stars, and
another broad (12-nm FWHM) emission at 710 nm is likely to be a
blend of C II lines, also found in Wolf-Rayet stars.  Narrow
emission of He I at 706.5, 667.8, and 587.5 nm are detected, as
well as weak [O III] at 436.3 nm.  Na I absorption with an
equivalent width of 0.07 nm is measured.  The redshift of the
narrow He I lines is 840 km/s.  SN 1983K (in NGC 4699, redshift of
1318 km/s) reached a maximum of B = 12.4."

     S. A. Ilovaisky and C. Chevalier, Observatoire de Haute-
Provence (OHP), write:  "Optical CCD photometry of the counterpart
of the transient Aql X-1, using a 15-min exposure obtained by A.
Boselli (Laboratoire d'Astronomie Spatiale)  with the 1.2-m OHP
telescope on Mar. 6.2 UT, shows the object at V = 16.95 +/- 0.02.
This is already 0.5 mag brighter than the maximum level reached
during the 1997 Aug.-Sept. outburst and shows that the current
event, which started about Feb. 27 (IAUC 6828), may reach levels
comparable to those of the 1995 July-Aug. and 1997 Feb.-Mar.
events.  Monitoring will continue at OHP."

SUPERNOVA 1997dq IN NGC 3810
     Unfiltered magnitude estimate by T. Doi, Columbus, TX:  Mar.
3.24 UT, 16.8 (accidental discovery).

                      (C) Copyright 1998 CBAT
1998 March 6                   (6832)            Daniel W. E. Green

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