We study high energy processes that occur during the merger of a neutron star (NS) or a black hole (BH) with the core of a red supergaint (RSG). The merger powers a luminous event termed common envelope jets supernova (CEJSN), that might account for lightcurves of peculiar transients. In the CEJSN scenario the NS/BH accretes mass from its surroundings through an accretion disk as it spirals-in inside the RSG’s envelope and core. The compact object launches part of this mass as narrow jets that interact with their environment by depositing their kinetic energy in the envelope and core gas. These jets can serve as production sites of high energy neutrinos and r-process elements.

We started high-cadence monitoring observations of 6.7 GHz methanol masers from Dec. 2012 using Hitachi 32-m radio telescope (Yonekura et al.(2016). Observations have been conducted basically every day. On average, 13 hours of observations have been made per day, amounting to 4000–5000 hours per year. The cadence varies by sources: one observation in 1–50 days. In addition to already known 29 sources (Tanabe et al. 2023 and references therein), we have newly identified ∼20 sources with periodic flux variability. We have also detected 5 sources with sudden flux rises in 2019–2022, including G358.93–0.03 which was confirmed to be associated with the accretion burst.