Central Bureau for Astronomical Telegrams
IAUC 7437: 2000cm; 2000cn; 2000co
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Circular No. 7437
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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Phone 617-495-7244/7440/7444 (for emergency use only)
SUPERNOVA 2000cm IN ANONYMOUS GALAXY
S. Jha, P. Challis, and R. Kirshner, Harvard-Smithsonian
Center for Astrophysics, report that a spectrogram of SN 2000cm
(cf. IAUC 7436), obtained by P. Berlind on June 4.16 and 5.17 UT
with the F. L. Whipple Observatory 1.5-m telescope (+ FAST
spectrograph), reveals it to be a type-Ia supernova after maximum
light. The age of the supernova based on its spectral features
(Riess et al. 1997, A.J. 114, 722) is 14 +/- 3 days after maximum
light. Cross-correlation of the host-galaxy spectrum with emission
and absorption-line templates yields a recession velocity of 2170
+/- 30 km/s.
SUPERNOVA 2000cn IN UGC 11064
Jha et al. report that a spectrum of SN 2000cn (cf. IAUC 7436),
taken by M. Calkins on June 3.37 UT with the Whipple Observatory
1.5-m telescope (+ FAST spectrograph), reveals it to be a type-Ia
supernova well before maximum light. Adopting the NASA/IPAC
Extragalactic Database rescession velocity for the host galaxy
(7043 km/s), the supernova expansion velocities measured with the
Ca H and K and the Si II (rest 635.5 nm) features are 17 400 km/s
and 12 900 km/s, respectively. For typical type-Ia supernovae,
these high velocities imply an age of approximately 7 to 10 days
before maximum light (Jha et al. 1999, Ap.J. Supp. 125, 73).
M. Turatto, A. Pastorello, E. Cappellaro, and F. Cedrati,
Osservatorio Astronomico di Padova, write: "We obtained spectra
(range 350-750 nm, resolution 2 nm) on June 5.0 UT with the Asiago
1.82-m telescope (+ AFOSC), showing SN 2000cn to be of type Ia, but
very close to maximum. Si II 635-nm is measured at 624.0 nm.
This, combined with the known galaxy recession velocity (7050 km/s
as reported in NED), gives a photospheric expansion velocity of
12 500 km/s. Other strong absorptions are measured at 384, 440,
496, and 587 nm."
SUPERNOVA 2000co IN MCG +7-33-17
Jha et al. also report that a spectrum of SN 2000co (cf. IAUC
7436), taken by Berlind on June 4.28 UT as above, shows it to be a
type-II supernova at maximum light. The spectrum exhibits a flat
continuum with broad P-Cyg Balmer lines and He I.
Cross-correlation of the host-galaxy spectrum with an emission-line
template yields a recession velocity of 11 590 +/- 30 km/s. The
expansion velocity of the supernova, measured via the H-alpha
profile, is 7300 km/s.
(C) Copyright 2000 CBAT
2000 June 5 (7437) Daniel W. E. Green
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