Central Bureau for Astronomical Telegrams
IAUC 6776: 1997du; PKS 2155-304
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Circular No. 6776
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1997du IN ESO 241-G22
J. Maza, Department of Astronomy, University of Chile, reports
the discovery of a supernova (B about 18) by Roberto Antezana on a
plate taken by L. Gonzalez with the Maksutov telescope at Cerro El
Roble on Oct. 30.215 UT. SN 1997du is located at R.A. =
0h10m25s.43, Decl. = -46o29'30".9 (equinox 2000.0), which is 10".5
west and 4".6 north of the nucleus of the host galaxy. The object
was confirmed by M. Graham (University of Central Lancashire) on a
CCD frame taken at Cerro Tololo under nonphotometric conditions
using the 0.9-m telescope on Nov. 1.245 and 3.061 (the supernova
being 0.1 mag brighter on the latter date).
F. Patat, European Southern Observatory (ESO), writes: "I
obtained a spectrogram (range 320-1000 nm, resolution 1.1 nm FWHM)
of SN 1997du with the ESO 1.52-m telescope (+ Boller & Chivens
spectrograph) on Nov. 25.16 UT; a preliminary reduction of the
spectrum shows H-alpha, H-beta, H-gamma, and H-delta lines with
shallow P-Cyg profiles. The expansion velocities, deduced from the
absorption minima are as high as 8400 and 6800 km/s for H-alpha and
H-beta, respectively. Other detected lines include Na I 589.2-nm,
Fe II 501.8-nm and Fe II 516.9-nm, all of them showing P-Cyg
profiles. The redshift at the location of the supernova, computed
from the narrow H emission lines arising in an underlying H II
region, is z = 0.020. The blue continuum and these other features
are consistent with a type-II classification, about 4-6 weeks past
maximum light, even if the H-alpha line is rather weak compared to
the other spectral features."
PKS 2155-304
L. Chiappetti, Istituto di Fisica Cosmica e Tecnologie
Relative, CNR, Milan; and V. Torroni, BeppoSAX, Rome, on behalf of
the BeppoSAX collaboration on Steep Spectrum Blazars, report: "The
BL-Lac object PKS 2155-304, which recently entered a gamma-ray
bright phase (cf. IAUC 6774), was observed with BeppoSAX from Nov.
22.62 to 24.03 UT. The quick-look data indicate an approximate
flux of 2-3 x 10E-10 erg cmE-2 sE-1 in the band 2-10 keV, close to
the highest level ever reported (Treves et al. 1989, Ap.J. 341, 733;
Sembay et al. 1993, Ap.J. 404, 112). Strong luminosity variability
within the observation is clearly apparent. Continuing
observations at all wavelengths are urged."
(C) Copyright 1997 CBAT
1997 November 25 (6776) Daniel W. E. Green
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