The measured Faraday depth of the ISM, φ_ISM, toward PSR B0834+06, as determined from HBA observations using the LOFAR FR606, Superterp and SE607 stations. These are plotted as a function of the geographic latitudes of the stations. The data points are offset slightly in latitude for ease of comparison. The measurements are also compared with the range in airmass calculated for the station location toward PSR B0834+06 for the duration of the observations (red triangles, right axis). The ionFR model was run using both TEC data from CODE (green squares) and ROB (blue points).