SERENDIPITOUS DISCOVERY OF A PROJECTED PAIR OF QSOs SEPARATED BY 4.5 arcsec ON THE SKY

Abstract

We present the serendipitous discovery of a projected pair of quasi-stellar objects (QSOs) with an angular separation of Delta theta = 4.50 arcsec. The redshifts of the two QSOs are widely different: one, our program target, is a QSO with a spectrum consistent with being a narrow line Seyfert 1 active galactic nucleus at z = 2.05. For this target we detect Ly alpha, C IV, and C III]. The other QSO, which by chance was included on the spectroscopic slit, is a Type 1 QSO at a redshift of z = 1.68, for which we detect C IV, CIII], and Mg II. We compare this system to previously detected projected QSO pairs and find that only about a dozen previously known pairs have smaller angular separation.