around 30 hours for each galaxy. We only use the broad band data to produce continuum maps. The narrow band continuum images are too shallow to make any meaningful contribution to our analysis.

We use <span style="font-variant:small-caps;">miriad</span> v1.5 to reduce the data. An automatic flagging for radio frequency interference based on Stokes V properties is executed right after applying calibration tables. Manual flagging is also applied if necessary. We take several iterations to self-calibrate the data to improve the phase and/or amplitude calibration. All the visibility data from different configurations are combined together to produce dirty maps, using $\mathrm{robust}=0$ weighting, to provide a compromise between sensitivity and resolution. We clean the dirty map in an area of $1.25^{\circ}\times1.25^{\circ}$ around our galaxy. If there are strong sources at the edge of the beam, we expand our clean area to make sure they are also cleaned, or subtract those strong sources directly from visibility data to improve image quality. The rms threshold to stop cleaning is set around $3\times10^{-5}{\ensuremath{\,\mathrm{Jy}}}$, but could be manually adjusted according to actual data quality. The restored radio continuum images of LVHIS galaxies are displayed in Appendix \[sec:radio\_image\]. The size of the synthesis beam varies significantly, due to 