Central Bureau for Astronomical Telegrams
IAUC 8553: 2005cs; 2005cn, 2005cr
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Circular No. 8553
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
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Phone 617-495-7440/7244/7444 (for emergency use only)
SUPERNOVA 2005cs IN M51
Wolfgang Kloehr, Schweinfurt, Germany, reports his discovery
of an apparent supernova (mag about 14) on CCD frames taken with a
0.20-m reflector on June 28.907 and 28.928 UT, with a weak earlier
image of the new object (at mag perhaps 16) also found by Kloehr on
a frame taken on June 27.933. Kloehr gave the position for SN
2005cs as R.A. = 13h29m53s.37, Decl. = +47o10'28".2 (equinox 2000.0),
which is 15" west and 78" south of the center of M51 (= NGC 5194).
Nothing was visible at this location on earlier frames taken by
Kloehr on May 11 and 26, on an 'LRGB' image taken by R. Muendlein
on Feb. 5, or on a Digitized Sky Survey image. W. Li, University
of California at Berkeley, reports that a CCD image taken with the
Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory on
June 30.25 confirms the new object at mag about 13.5; Li provides
position end figures 52s.85, 36".3, which is 67".3 south of the
nucleus of M51. A KAIT image taken on June 15.20 showed nothing at
this position (limiting mag about 19.0). H. Yamaoka, Kyushu
University, reports that K. Itagaki (Teppo-cho, Yamagata, Japan;
0.60-m telescope) obtained the following position end figures for
SN 2005cs from an unfiltered CCD image taken on June 30.484, when
the new object was at mag 14.3: 52s.78, 35".7; nothing was visible
at this location on Itagaki's image taken in poor conditions on
June 20.598 (limiting mag 17.0).
SUPERNOVAE 2005cn AND 2005cr
M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian
Center for Astrophysics, report that a spectrum (range 450-740 nm)
of SN 2005cn (cf. IAUC 8549), obtained on June 28.21 UT by M.
Calkins and R. Hutchins with the F. L. Whipple Observatory 1.5-m
telescope (+ FAST), shows it to be a type-Ia supernova with a
spectral-feature age (Riess et al. 1997, A.J. 114, 722) of about 3
(+/- 2) days after maximum light; the supernova expansion velocity,
derived from the minimum of Si II (rest 635.5 nm), and adopting the
NED recession velocity of 2065 km/s for the host galaxy (from da
Costa et al. 1998, A.J. 116, 1) is about 10000 km/s. A spectrogram
of SN 2005cr (cf. IAUC 8552), obtained on June 28.19, shows it to
be a type-Ia supernova, a few days before maximum light; the
supernova expansion velocity, derived from the minimum of Si II
(rest 635.5 nm), and adopting the NED recession velocity of 6437
km/s for the host galaxy (from Drinkwater et al. 1996, MNRAS 279,
595) is about 11000 km/s.
(C) Copyright 2005 CBAT
2005 June 30 (8553) Daniel W. E. Green
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