Laboratory line center tunings are stored on the SOUP laptop. When observed on the Sun, however, line centers change relative to disk position due to solar rotational Doppler effect (convective blue shift and gravitational red shift also have an effect). Before the SOUP filter can be used, line centers for each spectral line in the observing sequence must be calibrated at the location on the disk of the intended target.
Line calibration involves performing a line scan and then finding the offset from line centre.