The acceleration of the Universe in the light of supernovae -- The key role of the Cerro Tololo Inter-American Observatory

The discovery of acceleration and dark energy arguably constitutes the most revolutionary discovery in astrophysics in recent years. Cerro Tololo Inter-American Observatory (CTIO) played a key role in this amazing discovery through three systematic supernova surveys organized by staff astronomers: the “Tololo Supernova Program” (1986-2000), the Calan/Tololo Project (1989-1993), and the “High-Z Supernova Search Team” (1994-1998). CTIO’s state of the art instruments also were fundamental in the independent discovery of acceleration by the “Supernova Cosmology Project” (1992-1999). Here I summarize the work on supernovae carried out from CTIO that led to the discovery of acceleration and dark energy and provide a brief historical summary on the use of Type Ia supernovae in cosmology in order to provide context for the CTIO contribution.