SUBMILLIMETER CONTINUUM OBSERVATIONS OF COMET HYAKUTAKE (1996-B2)

We report submillimeter continuum observations of comet Hyakutake (199 6 B2) in the wavelength range 350 less than or equal to lambda less th an or equal to 2000 mu m. Submillimeter continuum emanates primarily f rom large (millimeter sized), solid particles in the coma. C/Hyakutake was the strongest source of cometary submillimeter radiation observed to date, allowing new measurements of unprecedented quality. The equi valent blackbody cross section at 800 mu m is (1.16+/-0.12)x10(2) km(2 ), corresponding to a dust mass M approximate to 1.8X10(9) kg and a du st mass production rate dM/dt approximate to 2.8X10(4) kg s(-1). The g radient of the emission spectrum is relatively flat, with an opacity i ndex beta=0.89+/-0.10. The cometary beta is comparable to values measu red in the circumstellar disks of young stars. A small map at 800 mu m shows a coma radial surface brightness variation that is compatible w ith steady emission of solids from the nucleus on timescales approxima te to 0.7 day. (C) 1997 American Astronomical Society.