Context :

Aims : We present photometric properties and distance measurements of 252 high redshift Type Ia supernovae ( 0.15 < z < 1.1 ) discovered during the first three years of the Supernova Legacy Survey ( SNLS ) .
These events were detected and their multi-colour light curves measured using the MegaPrime/MegaCam instrument at the Canada-France-Hawaii Telescope ( CFHT ) , by repeatedly imaging four one-square degree fields in four bands .
Follow-up spectroscopy was performed at the VLT , Gemini and Keck telescopes to confirm the nature of the supernovae and to measure their redshifts .

Methods : Systematic uncertainties arising from light curve modeling are studied , making use of two techniques to derive the peak magnitude , shape and colour of the supernovae , and taking advantage of a precise calibration of the SNLS fields .

Results : A flat \Lambda CDM cosmological fit to 231 SNLS high redshift Type Ia supernovae alone gives \Omega _ { M } = 0.211 \pm 0.034 \mathrm { ( stat ) } \pm 0.069 \mathrm { ( sys ) } .
The dominant systematic uncertainty comes from uncertainties in the photometric calibration .
Systematic uncertainties from light curve fitters come next with a total contribution of \pm 0.026 on \Omega _ { M } .
No clear evidence is found for a possible evolution of the slope ( \beta ) of the colour-luminosity relation with redshift .

Conclusions :