We present spectrograms of the faint V-drop (V(606) = 28.1, I(814) = 25.6)
galaxy pair HDF3-951.1 and HDF3-951.2 obtained at the Keck II Telescope.
Fernandez-Soto, Lanzetta, & Yahil (1998) derive a photometric redshift of z(ph)
= 5.28 (+0.34,-0.41; 2 sigma) for these galaxies; our integrated spectrograms
show a large and abrupt discontinuity near 7710 (+- 5) Angstroms. This break is
almost certainly due to the Lyman alpha forest as its amplitude (1 - fnu(short)
/ fnu(long) > 0.87; 95% confidence limit) exceeds any discontinuities observed
in stellar or galaxian rest-frame optical spectra. The resulting
absorption-break redshift is z=5.34 (+- 0.01). Optical/near-IR photometry from
the HDF yields an exceptionally red (V(606)-I(814)) color, consistent with this
large break. A more accurate measure of the continuum depression blueward of
Lyman alpha utilizing the imaging photometry yields D(A) = 0.88.
The system as a whole is slightly brighter than L*(1500) relative to the z~3
Lyman break population and the total star formation rate inferred from the UV
continuum is ~22 h(50)^-2 M(sun) yr^-1 (q(0) = 0.5) assuming the absence of
dust extinction. The two individual galaxies are quite small (size scales < 1
h(50)^-1 kpc). Thus these galaxies superficially resemble the Pascarelle etal
(1996) ``building blocks''; if they comprise a gravitationally bound system,
the pair will likely merge in a time scale ~100 Myr.Comment: 18 pages, 4 figures; accepted to A