S22B0007

As the booming development of wide-field survey facilities, great breakthroughs in time-domain astronomy have been achieved in 2010s. The large aperture of the Subaru telescope and the wide field of the Hyper Suprime-Cam (HSC) make the “MUlti-band Subaru Survey for Early-phase SNe Ia" (MUSSES) the most efficient project of studying Type Ia supernovae (SNe Ia) soon after their explosions. Here, we continuously propose a seven half-nights deep multiband imaging survey which is optimized to catch the first light of SNe Ia at redshifts below 0.2 as a part of the MUSSES2022 campaign. By balancing the observing depth, survey period, and total survey area of the Subaru/HSC observation, a dozen ultra-early SNe Ia with brightness >∼ 200 times fainter than the peak can be discovered, and particularly, the deepest photometry of early-phase SNe Ia by far can be promisingly achieved. The HSC deep multiband surveys that started to intensively monitor the same sky region in MUSSES winter campaigns from 2020 and early-phase spectroscopies via synergistic Gemini/GMOS observations not only provide a unique way to answer the long-standing progenitor issue of SNe Ia but also bring an important legacy value to the whole astronomical community in the era of space survey missions.

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