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IAUC 6925: 1998ck; 1998cg; W Com

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                                                 Circular No. 6925
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1998ck IN ESO 434-G20
     J. Maza, Department of Astronomy, University of Chile, reports
the discovery by Marina Wischnjewsky, on a T-Max 400 film taken by
L. E. Gonzalez with the Maksutov telescope at Cerro El Roble on May
31.969 UT, of an apparent supernova (B about 17) located at R.A. =
9h41m06s.00, Decl. = -29o06'17".7 (equinox 2000.0), which is 7"
west and 1" south of the center of the spiral galaxy ESO 434-G20.
The star was confirmed on direct CCD images obtained by I. Perez on
June 1 using the 1.0-m telescope at Las Campanas Observatory, but
it was not present on a film obtained on May 19.1 (B > 20).

     F. Patat, European Southern Observatory (ESO); and M. Turatto,
Osservatorio Astronomico di Padova, observed SN 1998cg with the ESO
3.6-m telescope (+ EFOSC2; range 330-750 nm, resolution 1.8 nm) on
May 30.07 UT at La Silla.  The reduced spectrum shows that this
object is indeed a supernova.  The spectral features are consistent
with a type-Ia classification, about 1 month after maximum light
(cf. Patat et al. 1996, MNRAS 278, 111).  The spectrum is dominated
by several emission lines with the usual P-Cyg profiles,
superimposed on a red continuum.  Most of the lines arise from Si
II, S II, Fe II, and Fe III.  The redshift of the parent galaxy,
estimated from the H-alpha line, is 0.119, which confirms that the
parent galaxy is a foreground object with respect to the cluster
Abell 1514.

     G. Tagliaferri and G. Ghisellini, Osservatorio Astronomico di
Brera, Milan; and P. Giommi, BeppoSAX, Rome, on behalf of the
BeppoSAX ToO collaboration on blazars, report:  "This BL Lac object
(= ON 231) was observed with the BeppoSAX Narrow Field Instruments
on May 11.96-12.90 UT.  The source was bright, with variability by
a factor of about 3 detected only below 2 keV.  The source was well
visible in the Phoswich Detector System up to about 100 keV.  The
preliminary analysis indicates an average energy flux of 2.6 x
10E-11 erg cmE-2 sE-1 in the band 0.1-4 keV.  Above 4 keV, the
spectrum hardens dramatically, with a 4-100-keV flux of about 4 x
10E-11 erg cmE-2 sE-1.  The extremely flat high-energy spectrum
suggests a very high gamma-ray flux.  Continuing observations at
all wavelengths are urged."

                      (C) Copyright 1998 CBAT
1998 June 2                    (6925)            Daniel W. E. Green

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