Spectroscopic observations of eight supernovae at intermediate redshift^*

¹ LPNHE, CNRS-IN2P3 and Universities of Paris 6 & 7, 75252 Paris Cedex 05, France
² Univ. Paris-Sud, 91405 Orsay, France e-mail: christophe.balland@ias.u-psud.fr
³ APC, UMR 7164 CNRS, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France
⁴ LUTH, UMR 8102 CNRS, Observatoire de Paris, Section de Meudon, 92195 Meudon Cedex, France
⁵ Department of Physics, Stockholm University, 10691 Stockholm, Sweden
⁶ CENTRA-Centro M. de Astrofisica and Department of Physics, IST, Lisbon, Portugal
⁷ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK

Received: 12 October 2006
Accepted: 4 December 2006

Abstract

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  minimization against a series of model templates.

Results. The spectra range from to , including one spectroscopically underluminous SN Ia at . This set of spectra significantly increases the sample of well-observed type SN Ia  supernovae available in the range . 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.