S21B0078

We propose to observe the SXDS UltraDeep (UD) field with HSC in order to investigate the unexplored time domain of the variable Universe - the long and faint. To explore the long-timescale frontier of the variable Universe, we have been accumulating the time domain legacy data with HSC at the SXDS UD field in the last 2 seasons in the i and z bands with the median limiting magnitudes of 26.0 mag and 25.5 mag, respectively. We propose to add the 3rd season data as deep as the last 2 seasons. The proposed long-term survey can discover high-redshift pair-instability and superluminous SNe and intrinsically long-lasting SNe. Long-term AGN activities can also be investigated. Unknown long-timescale transients may be discovered. Obtaining the time domain data in this year is essential to identify long-lasting transient candidates to follow with JWST, which will be launched in late 2021. We have been discovering long-lasting faint transients in the last 2 seasons. The live long-lasting SNe to be observed in 2022 and later with JWST can show up in 2021 and it is required to keep accumulating the long-term time domain data in S21B to make full use of JWST.

This document was translated from L^AT_EX by H^EV^EA.