Different ways of handling invalid data in the SIR-OPERATOR step on a simulated data set with a Gaussian burst of interference in a few channels. Purple marks invalid data, yellow is detected as interference. The SIR-operator operates on the flag mask, hence the visibility values are not used. Top: input data. Centre-left: invalid data is counted as flagged data. Centre-right: Invalid data is counted as unflagged data. Bottom-left: invalid data is removed before applying the SIR-operator. Bottom-right: Invalid data is penalized with ρ = 0.1.