A procedure for observing the Sun and Moon near new moon at wavelength
s 0.87-8.6 mm is briefly described. The measured ratios of their brigh
tness temperatures are presented. The choice of the new Moon as the so
urce of a reference spectrum is substantiated. The resulting spectrum
of the quiet Sun is close to linear, and agrees well with submillimete
r solar observations and most absolute measurements at millimeter wave
lengths.