Clock offsets as a function of time for the calibrator observations that were used to calibrate observations in the HETDEX Spring Field region. The lines show the clock offsets for different calibration observations. The red lines are the clock solutions when 3C 295 was used as the calibrator and the black lines are when 3C 196 was used. The panels show the clock offsets for two core stations (CS) and two remote stations (RS), from the top left these are the following: CS003HBA0, CS026HBA0, RS305HBA, and RS509HBA. There are several discontinuities in the derived clock values, which are due to difficulties in converging on the precise clock solution (see van Weeren et al. 2016a), but only the median clock solutions are applied for calibration of the target field.