Detection of the 3.4- and 2.8-μm emission features in Comet Bradfield (1987s)

Abstract A CH emission feature at 3.4 μm was detected in Comet Bradfield (1987s). The spectral shapes of this feature and of an additional emission feature near 2.8 μm are similar to those seen in Comets Halley and Wilson (1986l). For resonance fluorescence, derived abundances of the CH bonds in Bradfield are comparable to those of Halley and Wilson, within the uncertainties in the water production rates at the times of the observations. For thermal emission, the relative abundances depend on the assumed temperatures of the emitting grains.