Comparison of the frequency-integrated time series of an observation of the NPBS before and after the flattening step. Top panel: part of the original time series with the tracking adjustment of the analogue beam of NenuFAR just before 720 s (blue dotted line). Bottom panel: same part of the time series after the flattening step. Red dashed lines indicate the positions of the short discontinuities every 1.7 s generated during the data conversion into an 8-bit filterbank.