Optical Continuum Reverberation Mapping of a Candidate IMBH in a Nearby Seyfert 1 Galaxy

To investigate the short-term variability and determine the size of the optical continuum emitting region of intermediate-mass black holes (IMBHs), we carried out high-cadence, multiband photometric monitoring of a Seyfert 1 galaxy J0249−0815 across two nights, together with a one-night single-band preliminary test. The presence of the broad H α component in our target was confirmed by recent Palomar/P200 spectroscopic observations, 23 yr after the Sloan Digital Sky Survey, ruling out the supernovae origin of the broad H α line. The photometric experiment was primarily conducted utilizing four-channel imagers MuSCAT 3 and 4 mounted on 2 m telescopes within the Las Cumbres Observatory Global Telescope Network. Despite the expectation of variability, we observed no significant variation (