Long-term sp. obs. of SN IIb/Ib 2022crv

We show that it retained a very thin H envelope and transitioned from an SN IIb to an SN Ib; prominent H{alpha} seen in the pre-maximum phase diminishes toward the post-maximum phase, while HeI lines show increasing strength. SYNAPPS modeling of the early spectra of SN 2022crv suggests that the absorption feature at 6200{AA} is explained by a substantial contribution of H{alpha} together with SiII, as is also supported by the velocity evolution of H{alpha}.

The light-curve evolution is consistent with the canonical stripped-envelope SN subclass but among the slowest. The light curve lacks the initial cooling phase and shows a bright main peak (peak M_V_=-17.82{\pm}0.17mag), mostly driven by radioactive decay of ^56^Ni. The light-curve analysis suggests a thin outer H envelope (Menv~0.05M_{sun}_) and a compact progenitor (Renv~3R_{sun}_).