2010CBET.2575....2P

J. Parrent, D. A. Howell, P. E. Nugent, M. Sullivan, and D. Murray, on behalf the "Palomar Transient Factory", confirm the discovery of this supernova in NGC 1954. A CCD spectrum (range 350-950 nm) was taken with the Gemini South telescope on Dec. 7 UT. Matches to other spectra using "Superfit" (Howell et al. 2005, Ap.J. 634, 1190) indicate that 2010ko is a type-Ia supernova close to or before maximum light at an approximate redshift of z = 0.01. Assuming this redshift, the absorption minimum of the Si II 635.5-nm line displays a blue- shifted velocity of 11400 km/s. Further inspection of the spectrum reveals a stronger-than-normal Si II 580-nm absorption line, similar to those observed in subluminous type-Ia supernovae. If 2010ko is subluminous, an apparent absence of Ti II lines near 420 nm suggests that the supernova is only slightly sub- luminous. A Palomar image taken on Dec. 2.27 shows 2010ko at magnitude R = 17.5 ± 0.3 (with respect to USNO-B1-catalogue data).