Program: GS-2022B-Q-112

We propose to obtain spectra of infant (i.e., discovered within a few hours to days from the explosion) supernovae (SNe) and rapidly-evolving transients discovered by the KMTNet Supernova Program (KSP) during their post-infant phases (i.e. a few days to several weeks/months post-explosion) using the standard Gemini ToO triggers. The proposed observations will provide us with crucial information for investigating their type/subtype, photospheric properties, potential binary companions via stripped/ablated materials from the optically-thin nebular phase > 200 days post-explosion, distribution of nucleosynthetic products from deep ejecta layers revealed in the late-time evolution, as well as host galaxy properties. Combined with the data to be obtained from our companion proposal of "Rapid Spectroscopy of Infant Supernovae and Rapidly-Evolving Transients Discovered by the KMTNet Supernova Program" focused on understanding their elusive infant phase evolution, the proposed observations are expected to provide information that can significantly enhance our understanding of their origin and nature. Considering that post-infant phase information can be obtained with latency of a few days, we request 4 "standard" ToO triggers of GMOS-S spectroscopy for infant SNe and rapidly-evolving transients.