Electronic Telegram No. 174
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html


SUPERNOVAE 2005cp AND 2005cs
     M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center
for Astrophysics, report that a spectrogram (range 340-740 nm) of SN
2005cs (cf. IAUC 8554), obtained by R. Hutchins on June 30.23 UT with the
F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a young
type-II supernova.  The spectrum consists of a blue continuum and P-Cyg
profiles of the Balmer and He lines.  Adopting the NED recession velocity
of 600 km/s for the host galaxy (from Brian et al. 1996, Ap.J. 473, 130),
the expansion velocity derived from the minimum of the H_beta line is
about 7500 km/s.  Zero-velocity interstellar Na I D absorption with
an equivalent width of about 0.02 nm is detected in the spectrum of SN
2005cs, indicating gas along the line-of-sight in our galaxy and thus
suggesting some reddening by dust.  Schlegel et al. (1998, Ap.J. 500, 525)
estimate E(B-V) = 0.035 mag of Galactic reddening along the line-of-sight
to M51.  Interstellar Na I D absorption is detected also at the redshift
of the host galaxy, with comparable equivalent width, suggesting some host
galaxy extinction.
     Modjaz et al. add that a spectrum (range 350-740 nm) of SN 2005cp
(cf. IAUC 8550), obtained on June 30.43 UT by Hutchins, shows it to
be a type-IIn supernova.  The spectrum consists of a blue continuum,
indicating young age, and Balmer emission lines with a narrow component
of about 400 km/s (FWHM) superposed on a weaker and broader component
of about 4000 km/s (FWHM), after removing the NED recession velocity of
6616 km/s for the host galaxy (from Falco et al. 1999, PASP 111, 438).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the formal IAU Circulars.

                         (C) Copyright 2005 CBAT
2005 June 30                     (CBET 174)               Daniel W. E. Green