Upper panel: 345 GHz flux density of the flux calibrators used by the ALPINE survey (the J1058+0133, J0854+2006, and J0522−3627 quasars) as a function of time. The gray areas indicate when the ALPINE targets were observed (see Sect. 2.1). The only quasar used for CDFS targets (J0522−3627) is plotted with a dashed line, while solid lines are used for the calibrators of COSMOS sources. Lower panel: spectral index versus time. This spectral index is estimated using the band-7 and band-3 flux from the calibrator monitoring performed by the observatory (see Sect. 2.3).