  Emission lines in hydrogen can be used to measure the approximate redshift of
the reionization of the universe. This is an important measurement given the
lack of a convincing theoretical prediction of this epoch. There is a rapid
change in absorption at the reionization event, which can leave sharp features
in the spectrum of recombining hydrogen. These features in the near infrared
background permit us to measure the redshift at which reionization occurs. We
have calculated these signals based on numerical simulations of the Lambda-CDM
cosmogony.
