Continuum emission from FIFI-LS at wavelengths below 100 μm. The maps show (from top to bottom) the distribution of continuum emission with contours in the vicinity of the [O III] line at 51.81 μm (5, 15, and 30σ), the [O I] line at 63.18 μm (10, 15, and 20σ), and the [O III] line at 88.35 μm (10, 15, and 30σ). The magenta and blue stars show the center of DR21-1 core (Cao et al. 2019) and the center of the explosive outflow (Guzmán Ccolque et al. 2024). The black dot indicates the continuum center from 2D Gaussian fitting (see Table A.2), and the beam size is shown for the [O I] line at 63.18 μm as an orange circle.