M. Riello, S. Benetti, G. Altavilla, A. Pastorello, and M. Turatto, Osservatorio Astronomico di Padova; E. Cappellaro, Osservatorio Astronomico di Capodimonte; and P. Ruiz-Lapuente, Barcelona University, communicate that a spectrum (range 325-800 nm) of SN 2002cs (cf. IAUC 7891), obtained on May 7 with the Telescopio Nazionale Galileo (+ Dolores spectrograph), shows it to be a type-Ia supernova 2 +/- 2 days before maximum light (from spectral features); assuming the NASA/IPAC Extragalactic Database (NED) recession velocity of 4728 km/s for the host galaxy, the supernova expansion velocity is about 15700 km/s from the Si II 635.5-nm absorption. Matheson et al. confirm that a spectrum of SN 2002cs, obtained by Calkins on May 7.38, shows it to be a type-Ia supernova near maximum; also adopting the NED recession velocity for NGC 6702, they find the supernova expansion velocity to be about 15900 km/s for Si II (rest 635.5 nm), and the spectral- feature age of the supernova was determined to be 1 +/- 2 days before maximum light, for which the high expansion velocity is unusual. Chornock et al. remark that inspection of CCD spectra, taken as above at Lick, reveals that SN 2002cs is a supernova of type Ia, closely resembling SN 1994D near maximum light.
International Astronomical Union Circular
- Pub Date:
- May 2002