2005IAUC.8555....1M

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 8553), 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.