Light curves of five type Ia supernovae at intermediate redshift

Abstract

Aims. We present multi-band light curves and distances for five type Ia supernovae at intermediate redshifts, 0.18 < z < 0.27. Methods. Three telescopes on the Canary Island of La Palma, INT, NOT, and JKT, were used for discovery and follow-up of type Ia supernovae in the g' and r' filters. Supernova fluxes were measured by simultaneously fitting a supernova and host galaxy model to the data, and then calibrated using star catalogues from the Sloan Digital Sky Survey. Results. The light curve shape and colour corrected peak luminosities are consistent with the expectations of a flat ΛCDM universe at the 1.5σ level. One supernova in the sample, SN1999dr, shows surprisingly large reddening, considering both that it is located at a significant distance from the core of its host (~4 times the fitted exponential radius) and that the galaxy can be spectroscopically classified as early-type with no signs of ongoing star formation.