Integrated optical depths as a function of the principal quantum number for both data sets (Data-1 and Data-2) and for those previously reported in the literature (Ershov et al. 1984, 1987; Payne et al. 1989, 1994). We find good agreement between the measurements made over the whole remnant from the two LOFAR data sets and with those in the literature. We also find that the integrated optical depths of the RRLs are higher over the bright hotspot component with respect to the measurements over the whole remnant, implying that there is likely small-scale structure in the absorbing gas distribution.