SIMBAD references

In a pilot search for high-redshift radio quasi-stellar objects (QSOs), we have obtained spectra of 55 FIRST sources (S_1.4 GHz>1 mJy) with very red {formmu2} (O-E>3) starlike optical identifications. 10 of the candidates are QSOs with redshifts 3.6<z<4.4 (four were previously known), six with {formmu4} z>4. The remaining 45 candidates comprise: one z=2.6 broad-absorption-line (BAL) QSO; three low-redshift galaxies with narrow emission lines; 18 probable radio galaxies; and 23 M stars (mainly misidentifications). The success rate (high-redshift QSOs/ spectroscopically-observed candidates) for this search is 1/2 for {formmu6} S_1.4 GHz>10 mJy, and 1/9 for S_1.4 GHz>1 mJy. With an effective search area of 4030deg², the surface density of high-redshift {formmu8} (z>4) QSOs discovered with this technique is 0.0015deg^–2.