Null tests at 545 GHz. Left: difference spectra obtained by nulling the signal in the half-ring temperature map before correlating it with our nominal φ reconstruction. Middle: temperature signal nulled using different detectors at 545 GHz. Right: temperature signal nulled using the first and second survey maps. The black error bars correspond to the scatter measured within an ℓ bin, while the coloured bands correspond to the analytical estimate. Except for the survey null test (see text for details), these tests are passed satisfactorily, as illustrated by the quoted χ² and N_dof, thus strengthening confidence in the cosmological nature of our signal.