NICER observation list: Target ID 263601

Understanding the corona and disk-coronal interaction is a forefront challenge in black hole systems. While NuSTAR is the leading instrument at probing the high-energy spectral reflection component, NICER provides a complementary view of the thermal accretion disk. Both components are very strong for Cyg X-1, but the disk is cool and out of reach for NuSTAR alone. This proposal is a continuation of a previously approved NuSTAR Cycle 3 program on Cyg X-1 using the uniquely powerful capability of combined continuum and reflection modeling provided with both instruments together. By chance, our first program covered the soft state only. We propose to expand and target hard states and request 3x20 ks NuSTAR (3x4 ks NICER) observations of Cyg X-1 for triggered monitoring of hard states.