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An overview of the distribution of the extraplanar Hi (purple contours) and cold dust (in color); the Hi is smoothed to 22" spatial resolution. For comparison, optical isophotes are added in red. The Hi spurs are numbered as introduced in ref. 9. The axis labels are given in arc minutes from the center of NGC 4631 on the lower and left sides; the other sides gives the projected length scale for an assumed distance of 7.5 Mpc.
