NICER observation list: Target ID 355801

Black hole astrophysics is a fundamental tool in studying the accretion and ejection physics in the strongest gravity regime. The spectral technique reflection spectroscopy and timing technique reverberation mapping could reveal the geometry and properties of disk and corona in the innermost regions. With recent cutting-edge reverberation models, it is promising to settle the disk truncation controversy in the hard state, to track the corona outflowing velocity and reverberation lag behavior that indicates a changing coronal geometry, and to find more evidence for the hysteresis effect we previously see with NICER. The ultimate goal is to find clues on the state transition mechanism and the disk-corona-jet relation in black hole binaries.