  Motivated by recent evidence that the epoch of reionization of hydrogen may
have ended at a redshift as low as z~6 we consider the detectability of the
sources responsible for this reionization. The main idea is that reionization
places limits on the mean surface brightness of the population of reionization
sources. Reducing the number of model-dependent assumptions to a minimum, we
discuss the observability of these sources with existing and planned
telescopes. We define a family of models characterized by two parameters: the
Lyman continuum escape fraction f_c from the sources, and the clumpiness
parameter C of the intergalactic medium. The minimum surface brightness model
corresponds to a value of unity for both parameters. We find that the detection
of the non-ionizing UV continuum of the reionization sources will be difficult
to accomplish before the launch of JWST if these sources have a mean surface
brightness close to the minimum value. However, if the values of f_c and C are
more realistic, the reionization sources may well be detected by HST before
JWST, perhaps by exploiting gravitational lensing amplification by foreground
clusters of galaxies. Instead of a detection in the continuum, one may attempt
to detect the Lyalpha emission line by narrow-band imaging. Present Lyalpha
searches at z>6 suggest that either the typical sources are fainter than dwarf
galaxies, or that the escape fraction of ionizing photons is much higher than
50%, so that there are no bright compact HII regions formed around the ionizing
sources.
