Program: GN-2019A-C-2

We propose monitoring observations of NGC 4395 for 2 nights in order to measure the time lag of Balmer line variations with respect to AGN continuum variations. The expected lag is the shortest among local Seyfert 1 galaxies, providing a unique test-bed for investigating the slope and validity of the size-luminosity relation and the uncertainty of the black hole mass estimators, which are universally used for high Eddington and low Eddington AGNs. We will obtain multi-epoch spectra with a ~6 min. cadence at least for 1 night, and measure the Halpha lag, which is expected to be within 1-2 hours based on our photometry reverberation-mapping study. Combined with the extensive photometry campaign, which will be simultaneously performed with a number of 1-m class telescopes, this project will provide strong constraints on the size-luminosity relation and our understanding of photoionization in the broad-line region.