Comparison between the 1.4 mm continuum (white contours) and the glycolaldehyde spatial distributions (colour scale and green contours) towards (from top to bottom) NGC 1333-IRAS2A1, NGC 1333-IRAS4A, NGC 1333-IRAS4B1, and NGC 1333 SVS13-A. For continuum, first contours and steps correspond to 5σ (14 mJy beam^-1) and 10σ, respectively. The ellipses show the PdBI synthesised beam (HPBW) for the continuum (white, see Table 1) and glycolaldehyde images. The HPBWs for the glycolaldehyde images at 1.4 mm are: 082 × 070, 32° (NGC 1333-IRAS2A1), 108 × 081, 19° (NGC 1333-IRAS4A), 108 × 083, 20° (NGC 1333-IRAS4B1), and 106 × 080, 20° (NGC 1333 SVS13-A). The HPBWs for the glycolaldehyde images at 1.3 mm are: 082 × 070, 32° (NGC 1333-IRAS2A1), 072 × 044, 21° (NGC 1333-IRAS4A), 072 × 044, 21° (NGC 1333-IRAS4B1), and 071 × 043, 21° (NGC 1333 SVS13-A). Left panels: glycolaldehyde distribution refers to the sum of the 7_6,2–6_5,1 and 7_6,1–6_5,2 emission with (220.2 GHz, E_u = 37 K; see Tables A.1–A.4). First contours and steps correspond to 5σ (90, 90, 75, and 55 mJy beam^-1 km s^-1 respectively for NGC 1333-IRAS2A1, NGC 1333-IRAS4A, NGC 1333-IRAS4B1, and NGC 1333 SVS13-A) and 3σ, respectively. Right panels: glycolaldehyde distribution refers to the 22_2,21–21_1,20 emission (232.3 GHz, E_u = 135 K; see Tables 2–5). First contours and steps correspond to 5σ (100, 110, 50, and 60 mJy beam^-1 km s^-1 respectively for NGC 1333-IRAS2A1, NGC 1333–IRAS4A, NGC 1333-IRAS4B1, and NGC 1333 SVS13-A) and 3σ, respectively.