Spectrum of the C₂H N = 1–0 line. The different hyperfine components are indicated with their relative intensities for the SW (top) and NE (bottom) absorptions. Note the clear detection of the two strongest hyperfine components arising from FG0.89NE. The red curve shows the LTE synthetic spectrum, taking column densities of 1.3 × 10¹⁵ and 4 × 10¹³ cm^-2 toward the SW and NE images respectively, and a rotation temperature of 5.14 K.