Right: the ¹²CO 6–5 spectral map of IRAS 4A and 4B over the 240″  ×  240″ mapping area. Individual spectra are shown on the T_MB scale from –2 K to 12 K and velocity scale from –20 km s^-1 to 30 km s^-1. The outflows of IRAS 4A and 4B are overplotted over the entire spectral map. The map is centered on IRAS 4A. The contour levels start from 3σ (15 K km s^-1) with an increasing step size of 2σ (10 K km s^-1). Left: envelopes of IRAS 4A and 4B at the 10 K radius are shown together with the beam-sizes compared. See Fig. 1 caption and Sect. 3.2.1 for the details and the positions at which deep spectra are obtained.