HST/WFC3 1.6 μm image of the region around SMM J0658. The blue contours show the CO(1–0) integrated intensity of both images of SMM J0658 and, red contours show the CO(3–2) integrated intensity. The 7 mm continuum emission from the z = 0.35 galaxy to the south is indicated by yellow contours. The contour levels of the CO images are 3, 3.5 and 4σ, and those of the continuum image are 7, 9, 11 and 13σ. The two black squares indicate the locations of the two infrared Spitzer images, A to the east and B to the west (Gonzalez et al. 2009). CO(1 − 0) emission is seen at the positions of both images, but CO(3–2) emission is only seen at image B. The low significance of CO(3–2) at image A can also be seen in the spectrum (Fig. 4) The gray line between images A and B is the critical line, derived from the lensing model for a source redshift of z = 2.7 (Gonzalez et al. 2009), very similar to the redshift derived from the CO observations. The white circle shows the extent of the ATCA FWHM primary beam for the CO(3–2) observations; the primary beam at 7 mm is larger than the field displayed here. The offsets seen between the various components are discussed in Sect. 4.3.