We present observations of six Class 0 protostars at 3.3 mm ( 90 GHz ) using the 64-pixel MUSTANG bolometer camera on the 100-m Green Bank Telescope .
The 3.3 mm photometry is analyzed along with shorter wavelength observations to derive spectral indices ( S _ { \nu } \propto \nu ^ { \alpha } ) of the measured emission .
We utilize previously published dust continuum radiative transfer models to estimate the characteristic dust temperature within the central beam of our observations .
We present constraints on the millimeter dust opacity index \beta between 0.862 mm , 1.25 mm , and 3.3 mm . \beta _ { mm } typically ranges from 1.0 to 2.4 for Class 0 sources .
The relative contributions from disk emission and envelope emission are estimated at 3.3 mm .
L483 is found to have negligible disk emission at 3.3 mm while L1527 is dominated by disk emission within the central beam .
The \beta _ { mm } ^ { disk } \leq 0.8 - 1.4 for L1527 indicates that grain growth is likely occurring in the disk .
The photometry presented in this paper may be combined with future interferometric observations of Class 0 envelopes and disks .