NICER observation list: Target ID 770601

Cyg X-1 and Cyg X-3 are among the best studied X-ray sources in the sky. This makes them ideal laboratories for studying accretion onto compact objects. Combined IXPE and XL-Calibur polarimetric observations that cover the 2 80keV energy range have the potential to distinguish corona geometries in Cyg X-1 and to confirm the nature of the obscuring funnel in Cyg X-3. We request joint IXPE and NICER observations of Cyg X-1 and Cyg X-3 to coincide with the XL-Calibur flight. The distinguishing feature of these new observations will be the availability of near-contemporaneous 2 8keV and 15 80keV polarization information. By combining the broad-band polarimetric information and spectral information from NICER, we will make use of the unique opportunity provided by the XL-Calibur flight.