Structure of L1521E. Left: integrated intensity of CH₃OH (black contours) overplotted on integrated intensity of C¹⁷O. The black dot shows the peak of the 1.2 mm emission. The black triangle shows the peak of the H₂ column density derived from the Herschel/SPIRE data. The CH₃OH contour levels start from 6σ rms in steps of 6σ rms, with a 3σ rms level of 0.07 K km s⁻¹. Right: integrated intensity of N₂H⁺ (black contours) and distribution of 1.2 mm emission (white contours) overplotted on integrated intensity of C¹⁷O. The black dot shows the peak of the 1.2 mm emission. The black triangle shows the peak of the H₂ column density derived from the Herschel/SPIRE data. The N₂H⁺ contour levels start from 6σ rms in steps of 4σ rms, with 3σ rms level of 0.08 K km s⁻¹. For the 1.2 mm data the contours start from 6σ rms in steps of 3σ rms with a 3σ rms level of 5.38 mJy.