Spectroscopic observations of eight supernovae at intermediate redshift

Aims:We present spectra of six type Ia and two type II supernovae obtained in June 2002 at the William Herschel Telescope during a search for type Ia supernovae (SN Ia) at intermediate redshift.
Methods: Supernova type identification and phase determination are performed using a fitting technique based on a χ² minimization against a series of model templates.
Results: The spectra range from z=0.033 to z=0.328, including one spectroscopically underluminous SN Ia at z=0.033. This set of spectra significantly increases the sample of well-observed type SN Ia supernovae available in the range 0.15⪉ z⪉ 0.35. Together with the twelve supernovae observed by our team in 1999 in the same redshift range, they form an homogeneous sample of seventeen type Ia supernovae with comparable signal-to-noise ratio and regular phase sampling in a still largely unexplored region of the redshift space.

Section 5.2 and Figs. 3 to 10 are only available in electronic form at http://www.aanda.org