Broad line AGN are only rarely detected in faint (B=25, I=23, K=20) magnitude
limited samples, but the 5390 Å narrowband filter search yielded two such
objects at z=3.40 and lying near the HDF proper. This may suggest that they are
more common at fainter magnitudes and are picked up in the narrowband image
because of the strength of the emission lines. The two objects are circled on
this image and lie to the NW and SE of the HDF center. The region shown here is
approximately 2.6 × 4.0 arcmin2 in size.
These objects have nearly identical redshifts. The strong broad CIV and Lyman alpha emission lines make them extremely easy to identify.