The systematic study of the skies has revealed transient phenomena that have served as key probes over many decades for physics beyond reach at the laboratory. Thanks to advances in imaging capabilities, we are now able to detect and study rare astrophysical transients, e.g., those characterized by short time scales. Furthermore, the improved time resolution is critical for the understanding of the origin of stellar explosions, e.g., Type Ia supernovae used to measure the expansion rate of the Universe.
I will present two new projects at the Oskar Klein Centre, the intermediate Palomar Transient Factory and the Zwicky Transient Facility, two leading facilities in the study of astronomical transients at optical wavelengths.