Transients with fast brightness variance in UV/optical (“fast transients"), such as early-phase supernovae (SNe), fast blue ultraluminous transients (FBUTs), are of great interest in time-domain astronomy. Given the rapid brightness variance of fast transients and relatively shallow limits of transient surveys led by (sub-)meter class telescopes, observations of fast transients soon after their occurrences are still limited. From S23B, a significant number of fast transients will be routinely discovered by the 2.5-m Wide Field Survey Telescope (WFST), a new generation survey facility that is designed for hunting fast transients with a unique deep (a g-band limiting mag of ∼24.0 in dark nights), high-cadence (hourly/daily), multi-band (u,g,r) survey mode. We herewith propose Gemini/GMOS or Subaru/FOCAS ToO observations for catching early spectral evolution of four most intriguing fast transients discovered by WFST in S23B as a pilot of the new generation East Asian fast-transient observation network. Combined with model analyses, we aim to substantially deepen the understanding on the progenitor and explosion of SNe and the power source of FBUTs.
This document was translated from LATEX by HEVEA.