Effects of apodization in the maps. Top: BINGO apodized mask format (5°). The zeros in the scale correspond to non-observed spots and the transition between the observed and non-observed regions is done through the apodization (pixels with values > 0 and ≤1). Bottom left: region centered (ℓ,b)=(270° , − 20° ), where the mask was applied to the 21 cm signal map (gnomonic projection). Bottom right: same configuration as bottom left for the total foreground map.