An Einstein search for X-ray emission from comet Bradfield (1979l)

X-radiation may result from active plasma phenomena in the interactions of comets with the solar wind. We have carried out a limited but sensitive search for soft X-radiation from Comet Bradfield (1979$\text{l}$), on 1980 Feb. 5. No X-radiation was detected at a level (3σ) of 1.7 × 10^?13 erg(cm²sec keV)^?1 in the 0.2 – 4.0 kev range. This corresponds to a limit on the power dissipated in the comet by non-thermal electrons of approximately 10¹⁹ ergs sec^?1, averaged over the 2568-sec exposure to the comet. This energy deposition is near the magnitude suggested by simple theoretical ideas, and further searches of appropriate comets both in soft X-radiation and at radio wavelengths seem warranted.