  The number of damped Ly-alpha absorbers (DLAs) currently known is about 100,
but our knowledge of their sizes and morphologies is still very sparse as very
few have been detected in emission. Here we present narrow-band and broad-band
observations of a DLA in the field of the quasar pair Q0151+048A (qA) and
Q0151+048B (qB). These two quasars have very similar redshifts z_em = 1.922,
1.937, respectively, and an angular separation of 3.27 arcsec. The spectrum of
qA contains a DLA at z_abs = 1.9342 (close to the emission redshift) which
shows an emission line in the trough, detected at 4 sigma. Our narrow-band
image confirms this detection and we find Ly-alpha emission from an extended
area covering 6x3 arcsec^2, corresponding to 25x12h^-2 kpc^2 (q0=0.5, H0 = 100h
km s^-1). The total Ly-alpha luminosity from the DLA is 1.2 x 10^43 h^-2 erg
s^-1, which is a factor of several higher than the Ly-alpha luminosity found
from other DLAs. The narrow-band image also indicates that qB is not covered by
the DLA. This fact, together with the large equivalent width of the emission
line from the Ly-alpha cloud, the large luminosity, and the 300 km s^-1
blueshift relative to the DLA, can plausibly be explained if qB is the sourceof
a Lyman-limit system. We also consider the relation between DLAs and
Lyman-break galaxies (LBGs). If DLAs are gaseous disks surrounding LBGs, and if
the apparent brightnesses and impact parameters of the few identified DLAs are
representative of the brighter members of the population, then the luminosity
distribution of DLAs is nearly flat, and we would expect that some 70% of the
galaxy counterparts to DLAs at z=3 are fainter than m_R=28.
