Near-infrared observations of Comet Bradfield (1974b)

Photometric observations of Comet Bradfield (1974b) were performed in the near-infrared region. The energy distribution of the comet was similar to the solar spectrum in 1.03-, 1.25-, and 1.65-μm bands, and a slight infrared excess was observed in 2.2-μm band. These features closely resemble Comet Kohoutek 1973XII. Compiling the data of the two comets, the near-infrared spectrum is interpreted as the sum of the scattered sunlight and the thermal radiation from the dust grains whose temperature is --350 K at 1 AU, A steep decrease of the flux density with the heliocentric distance was observed between the two days of observation. (auth.)