  Kilometer scale neutrino telescopes are now being constructed (IceCube) and
designed (KM3NeT). While no neutrino flux of cosmic origin has been discovered
so far, the first weak signals are expected to be discerned in the next few
years. Multi-messenger (observations combining different kinds of emission)
investigations can enhance the discovery chance for neutrinos in case of
correlations. One possible application is the search for time correlations of
high energy neutrinos and established signals. We show the first adaptation of
a Target of Opportunity strategy to collect simultaneous data of high energy
neutrinos and gamma-rays. Neutrino events with coordinates close to preselected
candidate sources are used to alert gamma-ray observations. The detection of a
positive coincidence can enhance the neutrino discovery chance. More generally,
this scheme of operation can increase the availability of simultaneous
observations. If cosmic neutrino signals can be established, the combined
observations will allow time correlation studies and therefore constraints on
the source modeling. A first technical implementation of this scheme involving
AMANDA-II and MAGIC has been realized for few pre-selected sources in a short
test run (Sept. to Dec. 2006), showing the feasability of the concept. Results
from this test run are shown.
