We observed comet Hale-Bopp with the Berkeley-Illinois-Maryland Associ
ation (BIMA) array at frequencies between 85 and 115 GHz and with the
VLA at 43 and 22.5 GHz during 1997 March and April. The continuum radi
ation of the comet was ''easily'' detected in the 3 mm wavelength band
, where a peak flux density of 12.8 +/- 0.65 mJy beam(-1) was obtained
for all the data averaged together (scaled to a geocentric distance o
f 1.322 AU). The beam size for this observation was 11.'' 9 x 8.'' 8.
The total flux density was 47 +/- 4 mJy. We believe that only about 2
mJy can be attributed to thermal emission from the nucleus itself; the
remaining emission is thermal emission from large (roughly millimeter
-sized or greater) grains in the comet's coma. Roughly 25% of the emis
sion comes from an unresolved source at the center (i.e., an area with
a radius of less than or similar to 4500 km), which is surrounded by
a much larger area of low-level emission, visible in the BIMA images u
p to distances of at least similar to 25,000 km. Most of this emission
can be reconciled with thermal emission from dust flowing away from t
he nucleus, although there is also clear evidence of distinct emission
features similar to 25,000 km to the southeast and southwest of the n
ucleus, suggesting former outbursts and/or dust jets. The spectral ind
ex of the millimeter emission is consistent with a thermal blackbody s
pectrum, while a comparison with data at submillimeter wavelengths sug
gests a steepening in spectral index at shorter wavelengths. The total
mass of the dust in the coma is at least a few times 10(11) kg, and t
he dust production rate is of the order similar to 10(6) kg s(-1)