The Role of NOAO in the Discovery of the Accelerating Universe

timing the observations to catch SNe soon after explosion. Most of the photometry of the newly discovered SNe was obtained with the CTIO 0.9-meter telescope, while the CTIO 1.5-meter and Blanco 4-meter telescopes provided most of the spectroscopy. Analysis of this well-observed and wellcalibrated SNe sample showed that the peak brightness of a Type Ia SN was correlated with the light-curve shape. Using the light curve, one could transform a relatively diverse set of Type Ia SNe into “calibratable” standard candles. Without this calibration, neither team could have obtained luminosity distances to high-redshift Type Ia SNe with the precision necessary to detect the subtle effect introduced by the acceleration of the expansion. These SNe also provided the low-redshift anchor for the cosmology derived from the high-redshift SNe. The Calan/Tololo survey was essential to the success of each cosmological program. The techniques for finding high-redshift SNe