A Supernova at z = 0.458 and implications for measuring the cosmological deceleration

摘要: We have begun a program to discover high-redshift supernovae ($z \approx$ 0.25--0.5), and study them with follow-up photometry spectroscopy. report here our first discovery, supernova at $z = 0.458$. The for this closely matches the lightcurve calculated redshift from template of well-observed nearby Type Ia supernovae. discuss measurement deceleration parameter $q_0$ using such supernovae, give best fit value assuming one is normal, unextincted Ia. describe main sources error in $q_0$, ways reduce these errors.