(Upper left) 3.6 μm IRAC image of the spiral galaxy NGC 6872 with X-ray contours superposed. X-ray contours are from a background-subtracted, exposure-corrected 0.5–2 keV Chandra X-ray image that was smoothed with a σ = 4″ Gaussian kernel. (Upper right) Nonstellar 8.0 μm IRAC image of NGC 6872 with X-ray sources from Table 6 superposed. The IRAC image has been smoothed with a 1.″5 Gaussian kernel to highlight the faint nonstellar emission along the full length of the tidal arms and trailing the galaxy. Red ellipses denote X-ray point sources, while the blue ellipse is NGC 6872's nucleus. The size of the ellipse for each X-ray source represents the 3σ wavdetect source region, set such that the percentage of source counts in the elliptical region corresponds to the 3σ point of a corresponding two-dimensional Gaussian distribution, and thus depends on both the number of counts in the source and the detector point spread function. (Lower left) The same 8.0 μm nonstellar image as the upper right panel with young star clusters (green Xs) from Bastian et al. (2005) superposed. (Lower right) The same 8.0 μm nonstellar image as in the lower left panel with H I contours from Horellou & Koribalski (2007) superposed.