Before calibrating the visibility data, we need to plot it and flag the blue channels 21 to 32 because of their low signal-to-noise ratio. Select VisSq, the uncalibrated raw (squared) visibility amplitude, and plot it versus channel. ... The data selection defines which data is to be used to compute the correlation parameters, with the exception that if the Option|Loop parameter is selected in the calibration widget, the channels are calibrated independently, doing every selected channel. ...