NICER observation list: Target ID 263101

The best laboratory for strong-field gravity is the inner 100s of kilometers around compact objects in low-mass X-ray binaries. The X-ray emission varies rapidly, notably in quasi-periodic oscillations (QPOs), which may be produced by general relativistic effects. Low-frequency QPOs from black holes and neutron stars share similar temporal and spectral properties, indicating that they have similar emission mechanisms, even though neutron stars have a surface and strong magnetic field in addition to general relativistic effects. With these proposed observations, we will use phase-resolved spectroscopy of two types of low-frequency QPOs to constrain and compare the emission mechanisms, to better understand accretion flows in the strong gravity regime.