The published data set consists of measurements performed by the passive sub-millimeter radiometer as part of the Microwave Radar and radiometer for Arctic Clouds (MiRAC; Mech et al., 2019) operated on board the Polar 6 research aircraft during six research flights during the HAMAG (Humidity profiles and Arctic Mixed-phase clouds as seen by Airborne W- and G-band radars) campaign, carried out in February 2024 in Kiruna. The measurement campaign is embedded in the Transregional Collaborative Research Centre TR 172 (ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3. The published data set comprises brightness temperature measurements taken at nadir view with respect to the aircraft's fuselage at six frequencies in the water vapor absorption band, centered at approximately 183.31 GHz, and two additional channels at 243 and 340 GHz. The brightness temperatures have not been corrected for aircraft attitude. The dataset has been quality-checked and is available in NetCDF format for each flight. Details on the instrument can be found in Mech et al. (2019).