We have studied the long-slit spectra of the HH 1/HH 2 complex with a spectral resolution coresponding to 55 km s-1 at H-alpha. The spatial coverage includes HH 1, the jet, HH 2, the regions between these objects, and regions of 25"-30" beyond HH 1 (toward the NW) and HH 2 (toward the SE). Most of our results are based on a detailed study of the spatial and velocity dependence of the intensity in the emission lines H-beta, H-alpha, [C I] lambda-lambda-9823, 9849, [N I] lambda-lambda-5198, 5200, [O I] lambda-lambda-6300, 6363, [S II] lambda-lambda-6716, 6731, [Fe II] lambda-5262, and [O III] lambda-lambda-4959, 5007. In a first step we have restricted ourselves to the investigation of the spatial dependence of intensities and derived quantities (integrating over velocities). Specifically we have studied the spatial variation of the electron density (derived from the [S II] lambda-lambda-6716, 6731 intensity ratio), the [O III]/H-beta (showing high-excitation regions), the [S II]/H-alpha (showing regions of low excitation), and the [S II]/[O I] ratios (giving supplementary density information). We have also studied radial velocities and velocity dispersions. The condensation of HH 2A' (which has brightened during recent years) shows a very high electron density N(e) approximately 1.3 x 10(4) cm-3. The density of the jet N(e) approximately 2 x 10(3) cm-3 is lower but relatively high for a jet. The extremely low excitation of the jet is convincingly shown by very high maxima in the [N I]/H-beta and [S II]/H-alpha ratios. Large velocity dispersions occur either in the HH objects or near (usually in front of) these objects. In front of HH 1, the large velocity dispersion of the [S II] and [O I] is correlated with large blueshifts of these lines. These results indicate that in front of HH 1, light is scattered by dust which is essentially at rest and which "sees" blueshifted lines from the rapidly approaching HH object. The observed blue wings of the [S II] and [O I] lines reach Doppler shifts of about approximately 300 km s-1, in good agreement with the velocities determined from proper motions. This shows that under the geometrical conditions which hold for the HH 1/HH 2 complex (i.e., with jet axis in the plane of the sky), velocities of matter in the plane of the sky can indeed be determined from Doppler shifts of dust-scattered lines. In a second step we look at the dependence of the electron density and line ratios on position and velocity. This permits us to identify, for example, line wings which are due to dust scattering because they still show the electron density and the degree of excitation of the original source. This approach confirms the suggestion that, for example, the [S II] lines in front of HH 1 are mostly due to dust scattering. It also shows that the blue wings seen in the strong lines at the position of the jet are due to dust scattering of light probably from parts of the jet close to the central source VLA 1. The position-velocity diagrams of N(e) for HH 1 and HH 2A' show interesting structures. We tentatively interpret these as being due to a bow shock with its axis in the plane of the sky in the case of HH 1 and a bow shock whose axis forms an angle of about 10-degrees with the plane of the sky in the case of HH 2A'. We report on the detection of highly redshifted faint line components of [S II] lambda-6731 and [O I] lambda-6364 in HH 2A'.
