Continuum energy distributions of quasars in the Palomar-Green Survey

Nearly simultaneous observations, from 0.3 to 2.2 microns, of the complete set of quasars found in the Palomar-Green survey are presented, along with 3.7 and 10.1 microns observations of a limited number of the quasars. The majority of the continua at rest frequencies between 10 to the 13.8th and 10 to the 15.3rd Hz are consistent with fits by two power-law slopes plus a '3000 A bump'. The spectral indices representing the lower frequency observations have a median value of -1.4, while those describing the higher frequencies have a median value of -0.2. The transition frequency between these slopes is close to 10 to the 14.5th Hz in the rest frame; the dispersion around this frequency is about one octave. A significant fraction of the low-redshift quasars show evidence of nebulosity within 5 arcsec of the quasar.