Three different displays of X‐ray surface brightness observed with ROSAT HRI centered on optical disks of NGC 4038/39; each display shows a gray‐tone representation of X‐ray brightness with contour levels superposed. (a) Data binned into 1^{﹩\arcsec﹩} pixels and smoothed with Gaussian of σ = 2^{﹩\arcsec﹩}; field of view is 3﹩\farcm﹩85 × 3﹩\farcm﹩85. Successive contours mark surface brightnesses of 3, 6, 9, 12, and 15 σ above background. (b) Data binned into 2^{﹩\arcsec﹩} pixels and smoothed with Gaussian of σ = 4^{﹩\arcsec﹩}; field of view is 3﹩\farcm﹩85 × 3﹩\farcm﹩85. Successive contours again mark surface brightnesses of 3, 6, 9, 12, and 15 σ above background. (c) Data binned into 2^{﹩\arcsec﹩} pixels and smoothed with Gaussian of σ = 16^{﹩\arcsec﹩}; field of view is 11﹩\farcm﹩87 × 11﹩\farcm﹩87. Successive contours mark surface brightnesses of 3 and 6 σ above background.