V_LSR, FWHM, and measurements of H₂D⁺ plotted over offset from the 850 μm dust peak of L183. The shaded region in the middle plot corresponds to the thermal broadening within the 5–12 K temperature range. The shaded regions in purple correspond to the errors reported in Caselli et al. (2008). The square, triangle, and circle refer to north, south, and 0′′ declination offsets, respectively. The blue and red symbols refer to offsets toward the east and west, respectively, while the black symbols correspond to 0′′ Right Ascension offsets. For example, a  40′′ offset can be represented by a red square (40′′ north-west), a black triangle (40′′ south), a blue circle (40′′ east), and so on.