Serendipitous discovery of a projected pair of QSOs separated by 4.5   arcsec on the sky
  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 programme target, is a QSO with a spectrum consistent with being a narrow line Seyfert 1 AGN at $z=2.05$. For this target we detect Lyman-$\alpha$, \ion{C}{4}, and \ion{C}{3]}. 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 \ion{C}{4}, \ion{C}{3]} and \ion{Mg}{2}. We compare this system to previously detected projected QSO pairs and find that only about a dozen previously known pairs have smaller angular separation. 
K. E. Heintz, J. P. U. Fynbo, J.-K. Krogager, M. Vestergaard, P.   M{\o}ller, M. Arabsalmani, S. Geier, P. Noterdaeme, C. Le...
astro-ph.HE astro-ph.GA