S21B0044

Early high-resolution spectroscopy is essential for understanding of progenitors of supernovae (SNe). Time-variable circumstellar (CS) signatures can be used to map the final stages of the progenitor stars through their mass-loss history. As the line widths are less than 100 km/s, high-resolution spectra are required. Thanks to recent high-cadence surveys, very early follow-up can be made to explore CS material in a new time domain than previously possible. We propose to obtain a time sequence for one core-collapse SN beginning within a week of explosion. In additional, time is requested to obtain similar data for several SNe within 1-2 weeks of explosion. This data will provide an expanding understanding of the poorly understood CS environment and thereby paint a generic picture covering various progenitors.

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