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IAUC 7017: V1333 Aql; 1998bw

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                                                 Circular No. 7017
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)

     S. A. Ilovaisky and C. Chevalier, Observatoire de Haute-
Provence (OHP), write: "CCD observations of the optical counterpart
of the Aquila X-1 recurrent x-ray transient have obtained with the
1.2-m OHP telescope during Sept. 8 to 18.  A V-band image taken on
Sept. 10.86 UT shows the object to be still in quiescence, but on
images taken by R. Mujica (Observatoire de Strasbourg) on Sept.
16.8 and 18.8, the object is 30 and 90 percent above the quiescent
level, respectively.  This brightening comes 200 days after the
March episode (IAUC 6828, 6832), and it probably signals the start
of a new activity cycle.  Monitoring will continue at OHP.
Observations at other wavelengths are encouraged."

SUPERNOVA 1998bw IN ESO 184-G82
     F. Patat, European Southern Observatory (ESO); and A. Piemonte,
Pontificia Universidad Catolica, on behalf of the ESO team (Lidman
et al., cf. IAUC 6895, plus J. Brewer), report:  "A low-resolution
spectrum (range 350-1000 nm, resolution 2.0 nm) of SN 1998bw was
obtained with the ESO 3.6-m telescope (+ EFOSC2) on Sept. 12.13 UT,
125 days after maximum light in B.  The object has definitely
entered its nebular phase, showing strong emissions of Na I D 589-
nm, [O I] 630-nm, [Ca II] 728-nm, and the Ca II infrared triplet.
Nevertheless, this supernova continues to be exceptional among the
known type-Ic events:  contrary to the expected spectral evolution
in the blue region, SN 1998bw shows strong emissions centered at
400, 460, and 527 nm.  While that at 400 nm is easily identified as
Ca II H and K, the other two lines are puzzling; they are the most
intense features after the [O I] 630-nm emission, and they have a
FWHM of about 16 nm.  If they are due to Fe II (455.5, 521.5 nm),
as the strong resemblance of this spectral region with that shown
by type-Ia supernovae would suggest, we are looking at a very rare
case of type-Iac supernova that shows emission features common to
both type-Ia and type-Ib/c events.  So far, only two other
supernovae have exhibited such a strange behavior:  SN 1990aj (see
Piemonte 1997, "Observational properties of SNe Ib/c",
http://athena.pd.astro.it/~supern/preprints.html) and SN 1993R
(Filippenko 1997, in Thermonuclear Supernovae, Canal et al., eds.,
Dordrecht: Kluwer, p. 795), but they suffer from scanty photometric
data.  We suggest a search for a possible coincidence of SN 1990aj
or SN 1993R with known gamma-ray bursts, to investigate further the
claimed association of type-Ib/c supernovae with this class of

                      (C) Copyright 1998 CBAT
1998 September 21              (7017)            Daniel W. E. Green

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