We have measured the laser induced fluorescence excitation spectrum of the origin of the DCO B∼(2A′)←X∼(2A′) transition under a variety of experimental conditions, ranging from cooled to 7K in a supersonic jet, to nascent in the photolysis of D 2 CO. By analysing successively more complex spectra we have derived rotational, centrifugal distortion, and spin-rotation coupling constants that provided the best fit to the experimental frequencies. Fluorescence lifetimes were measured for 35 rotationally-resolved excited states, which provided relative quantum yields for these states. Unlike HCO, the lifetimes showed only a weak dependence on N and K a , evincing a weaker coupling between the A∼ and B∼ states in DCO than HCO. Intensity ratios for pairs of transitions with the same lower state were used to extract the transition moment angle, θ=44.6±2.5° and the axis switching angle, ϕ=3.1±0.5° for the B∼–X∼ transition. Both angles are consistent with the expected change upon deuteration of HCO.