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An optically thin cirrus cloud was profiled concurrently with nadir‐pointing 1,064 nm lidars on 11 August 2017 over eastern Texas, including NASA's airborne Cloud Physics Lidar (CPL) and space‐borne Clouds and Aerosol Transport System (CATS) instruments. Despite resolving fewer (37% vs. 94%) and denser (i.e., more emissive) clouds (average cloud optical depth of 0.10 vs. 0.03, respectively), CATS data render a near‐equal estimate of the top‐of‐atmosphere (TOA) net cloud radiative forcing (CRF) versus CPL. The sample‐relative TOA net CRF solved from CPL is 1.39 W/m2, which becomes 1.32 W/m2after normalizing by occurrence frequency. Since CATS overestimates extinction for this case, the sample‐relative TOA net forcing is ~3.0 W/m2larger than CPL, with the absolute value reduced to within 0.3 W/m2of CPL due its underestimation of cloud occurrence. We discuss the ramifications of thin cirrus cloud detectability from satellite and its impact on attempts at TOA CRF closure. Coincident nadir 1,064 nm lidar measurements of optically thin cirrus clouds were collected from aboard a high‐altitude aircraft and the International Space StationThe relative top‐of‐the‐atmosphere (TOA) net cloud radiative forcing (CRF) solved from the two data sets reveal sensitivities to the algorithms used to derived cloud propertiesThe absolute TOA net CRF solved from the two data sets are consistent despite limited cloud detection capabilities in the ISS product