(a) ﹩20^{\prime \prime }\times 20^{\prime \prime }﹩ composite image of HD 163296 combining the data from the three orientations. The image is logarithmically scaled and oriented with north up and east to the left. Radial streaks in the image are due to differences in the PSF at the epoch of observation and in the calibration data (HST’s "breathing"). Dark, irregularly shaped polygons are voids produced by the intersection of the wedge structure in the three observations. The region of the most severe PSF residuals, interior to 1﹩\farcs﹩5, has been digitally masked out in this composite image. (b) Cartoon of the HD 163296 disk+knot system showing the orientation of the disk and the position of the knots relative to the disk.