Continuum-subtracted IRAM-PdBI spectra, maps, and position–velocity diagram of the CO(1–0) emission line of IRAS 23365+3604. Panels a) and b) show the spectra extracted from a circular aperture with a diameter of 5 arcsec and from the central pixel, respectively. For display purposes, the spectra are re-binned in channels of 54 km s^-1. In both panels the narrow core of the line is fitted with a single Gaussian function (red dashed line). c), d) Cleaned map of the emission integrated in the blue- and red-shifted CO(1–0) wings. Contours correspond to 1σ (1σ rms level of the two maps is 0.2 mJy beam^-1). The physical scale at the redshift of the source is 1.232 kpc arcsec^-1. e) Position–velocity diagram along the major axis of rotation. Inset f) highlights the rotation pattern traced by the narrow component of the CO(1–0) line; this also suggests the presence of a counter-rotating disk visible at large radii (i.e. up to about 8 arcsec from the nucleus, which correspond to ~10 kpc). Contours are in steps of 1σ (up to 7σ) in panel e), and 5σ in inset f); negative contours are in steps of 1σ (magenta dashed lines). Each pixel corresponds to 0.6 arcsec × 54 km s^-1 in diagram e), and to 0.3 arcsec × 27 km s^-1 in the inset f).