  With the observation of the gravitational wave event of August 17th 2017 and
then with those of the extragalactic neutrino of September 22nd, the multi
messenger astronomy era has definitely begun. With the opening of this new
panorama, it is necessary to have a perfect coordination of the several
observatories. Crystal Eye is an experiment aimed at the exploration of the
electromagnetic counterpart of the gravitational wave events. Such events
generated by neutron stars collision (or mergers) are associated with gamma-ray
bursts. It has actually been observed in the event GW170817 that there is an
X-ray counterpart associated with the GW consistent with a short gamma-ray
burst viewed off-axis. These X-ray emissions represent the missing
observational link between short gamma-ray bursts and gravitational waves from
neutron-star mergers. The experiment we propose is a wide field of view
observatory (2{\pi} of local observation) in the energy range from tens of keV
to few MeV designed to fly with International Space Station (ISS). The motion
along the ISS orbit will allow the experiment to scan the sky at 4? in 90
minutes. The Crystal Eye objectives will be: to alert the community about
events containing X-rays and low energy gamma-rays, to monitor long-term
variabilities of X-ray sources, to stimulate multi-wavelength observations of
variable objects, and to observe diffuse cosmic X-ray emissions. With its
characteristics, Crystal Eye will provide the continuous exploration and
monitoring of the Universe after a Gravitational Wave event with a better
resolution than Fermi GBM. Thanks to its large field of view and its design, it
has the potentiality to be the trigger for those present X ray-astronomy
missions (Chandra, Swift, Integral XMM Newton) that are based on high angular
resolution pointing experiment but that have unfortunately a very small field
of view.
