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IAUC 6708: 1997cz; 1997cy; BL Lac

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                                                 Circular No. 6708
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/cfa/ps/cbat.html
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     The Mount Stromlo Abell Cluster Supernova Search Team (cf.
IAUC 6639) reports the discovery of an apparent supernova (V =
20.5) on V and R CCD images taken on July 19 by S. Sabine at the
Mount Stromlo 1.27-m telescope (+ Macho Camera).  SN 1997cz is
located near Abell 3565 at R.A. = 13h37m09s.39, Decl. =
-33o47'31".9 (equinox 2000.0).  A nearby star has position end
figures 13s.08, 36".4.  SN 1997cz was also present at approximately
the same magnitude on similar V and R frames taken on July 21 and
June 10, but it is not visible on images taken on Apr. 26 (limiting
mag R = 21).

     S. Benetti and A. Pizzella, European Southern Observatory; and
P. J. Wheatley, University of Leicester, report:  "A fully-reduced
CCD spectrum (range 320-880 nm, resolution 2.0 nm) of SN 1997cy
(cf. IAUC 6706), obtained on July 24.43 UT with the Danish 1.5-m
telescope (+ DFOSC), is dominated by an intense emission line with
a composite profile.  Its narrow component is centered at 698.4 nm
(FWHM = 4.0 nm), and it is superimposed on a broader one (centered
at about 697.0 nm, FWHM about 13.0 nm) that has a very steep red
wing.  If this feature is identified with H-alpha, then a redshift
of 0.0642 is deduced for this supernova.  The bluer part of the
spectrum shows strong and broad Fe II features resembling those
shown by some type-Ic supernovae near maximum; peaks are measured
at about 493.0 nm (FWHM about 15.8 nm), 529.0 nm (FWHM about 12.0
nm), and 580.0 nm (FWHM about 45.0 nm).  Another very broad
emission (FWHM about 70.0 nm) is centered at about 785.5 nm.  A
relatively faint H-beta emission is also present (peak at 518.0 nm,
FWHM = 2.7 nm).  Spectroscopic and photometric follow-up of this
peculiar type-II supernova is encouraged."

     F. Makino, J. Mattox, T. Takahashi, and J. Kataoka, Insitute
of Space and Astronautical Science (ISAS); and H. Kubo, Physical
and Chemical Research Institute (Riken), Wako, report:  "ASCA
observed this source during July 18.60-19.62 UT, yielding an
average x-ray flux of 2.6 x 10E-11 erg sE-1 cmE-2 (2-10 keV), which
is more than four times higher than that observed in its low state
with Ginga (Kawai et al. 1991, Ap.J. 382, 508).  The spectrum was
of power-law type with photon index of -1.44 +/- 0.01.  The flux
showed variation by a factor of 2 during the observation."

                      (C) Copyright 1997 CBAT
1997 July 24                   (6708)            Daniel W. E. Green

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