The Large Bright Quasar Survey. VII. The LBQS and FIRST Surveys

The source catalogue for the LBQS and the FIRST Survey are compared in theirregions of overlap. In the 270 deg^2 common to both surveys the LBQS contains\~100,000 stellar and ~40,000 non-stellar objects, while the FIRST cataloguecontains ~25,000 sources. Cross-correlation of these lists yields 67 positionalcoincidences between known LBQS quasars and FIRST sources and an additional 19stellar and 149 non-stellar positional coincidences with the radio catalogue.Spectroscopy of all the stellar matches and two-thirds of the non-stellarmatches produces eight new quasars. One BL Lac object, previously misclassifiedduring the LBQS survey is also identified. The straightforward fractionalincompleteness of the LBQS determined from this sample is 13+/-4%, in goodagreement with the published estimate of 10%. The distributions of the ratio ofradio-to-optical power, apparent magnitude and spectroscopic properties for thenew objects are consistent with those of the 67 LBQS-FIRST objects previouslyknown. The consistency of the optical and radio properties of the new objectswith those of the known quasars thus supports the conclusion that no newpopulation of objects, constituting more than ~7% of quasars detected by FIRST,has eluded the LBQS optical selection techniques. The percentage ofradio-detected quasars in the LBQS catalogue is found to be 12+/-2%,considerably smaller than the value of 25% advocated by White et al. (2000)based on the FBQS. Apparent differences in the form of the number-redshiftrelation for the LBQS and FBQS samples are shown to arise in large part fromthe very different optical passbands employed.Comment: 30 pages, 6 figures To appear in Astronomy Journal, August 200