  Imaging and spectroscopy with HST show that LBQS 0103-2753 (V = 17.8, z =
0.848) is a binary quasar with a separation of 0.3 arcsec or 2.3 kpc. This is
by far the smallest separation binary quasar reported to date. The two
components have very different spectra, including the presence of strong broad
absorption lines (BALs) in component A only. The emission-line redshifts, based
on the broad high ionization C IV lines, are z_A = 0.834 and z_B = 0.858; their
difference is 3900 km/s in velocity units. The broad C IV lines, however, are
probably not a good indicator of systemic redshift; and LBQS 0103-2753 A and B
could have a much smaller systemic redshift difference, like the other known
binary quasars. If the systemic redshift difference is small, then LBQS
0103-2753 would most likely be a galaxy merger that has led to a binary
supermassive black hole. There is now one known 0.3 arcsec binary among roughly
500 QSOs that have been observed in a way that would reveal such a close
binary. This suggests that QSO activity is substantially more likely for black
hole binaries at spacings ~2 kpc than at ~15 to 60 kpc. Between 1987 and 1998,
the observed Mg II BAL disappeared.
