  The purpose of this article is to alert Astronomers, particularly those using
spectroscopic surveys, to the fact that exotic astronomical objects (e.g.
quasars or active galactic nuclei) that send ultra-rapid quasi periodic pulses
of optical light would generate spectroscopic features that look like emission
lines. This gives a simple technique to find quasi periodic pulses separated by
times smaller than a nanosecond. One should look for emission lines that cannot
be identified with known spectral lines in spectra. Such signals, generated by
slower pulses, could also be found in the far infra-red, millimeter and radio
regions, where they could be detected as objects unusually bright in a single
narrow-band filter or channel. The outstanding interest of the technique comes
from its simplicity so that it can be used to find ultra-rapid quasi-periodic
oscillators in large astronomical surveys. A very small fraction of objects
presently identified as Lyman alpha emitters that do not have other spectral
features to confirm the Lyman alpha redshift, may possibly be quasi-periodic
oscillators. However this is only a hypothesis that needs more observations for
confirmation.
