Typical EBHIS and GASS baseline problems. The four panels show a position-velocity slice of the overlap-region datacube. Top left panel: difference between EBHIS and GASS, top right panel: GASS data, and bottom panels: EBHIS and GASS data with a zoomed-in intensity scale. The labeled features are: a) larger-angular scale baseline fluctuations in direct vicinity of the Milky Way disk H i profile in EBHIS data; b) baseline deficiencies around non-disk objects in GASS, caused by improper flagging; and c) increase in baseline level associated to the rectangular pattern visible in Fig. A.1. All colorbars show brightness temperature, T_B, in units of Kelvin. See text for further discussion.