Abstract Large excursion of the inflaton field can trigger interesting dynamics. One important example is a first-order phase transition in a spectator sector which couples to the inflaton. Gravitational waves (GWs) from such a first-order phase transition during inflation. an example of an instantaneous source. https://www.lightemupsequences.com/quick-find-Our-Seasons-The-World-in-Winter-Spring-Summer-and-Autumn-best-save/