The AGN content of the FBS

Thirty-four FBS objects are listed as QSOs in the Véron-Cetty & Véron (1998) catalogue. Two more have been shown to be QSOs by Hagen et al. (1998) and six have been identified in the present paper. There are therefore 42 known QSOs in the FBS, 41 being at high galactic latitude ($\vert b \vert$ > 30$^{\rm o}$). At high galactic latitude, all FBS objects associated with a RASS-BSC source have been identified. Among them, there are 25 QSOs. As about 60% of all PG QSOs are RASS sources, and assuming that this is true for the FBS QSOs, we should have a total of about 43 QSOs in the FBS catalogue. This suggests that the number of QSOs still to be found in the FBS catalogue is very small as 42 are already known.

All 114 AGNs from the PG survey have been observed at 5 GHz with the VLA (Kellerman et al. 1989); 35 (30%) have been detected with a flux density larger than 3 mJy. The same fraction (12/40) of the known FBS QSOs have been detected in the NVSS survey, confirming that the number of QSOs in the as yet spectroscopically unobserved FBS objects is small and probably cannot exceed 10, as the fraction of radio-detected QSOs would then drop below 25% and be significantly lower than the corresponding fraction for the PG survey.