  The ANTARES telescope observes a full hemisphere of the sky all the time with
a duty cycle close to 100%. This makes it well suited for an extensive
observation of neutrinos produced in astrophysical transient sources. In the
surrounding medium of blazars, i.e. active galactic nuclei with their jets
pointing almost directly towards the observer, neutrinos may be produced
together with gamma-rays by hadronic interactions, so a strong correlation
between neutrinos and gamma-rays emissions is expected. The time variability
information of the studied source can be obtained by the gamma-ray light curves
measured by the LAT instrument on-board the Fermi satellite. If the expected
neutrino flux observation is reduced to a narrow window around the assumed
neutrino production period, the point-source sensitivity can be drastically
improved. The ANTARES data collected in 2008 has been analysed looking for
neutrinos detected in the high state period of ten bright and variable Fermi
sources assuming that the neutrino emission follows the gamma-ray light curves.
First results show a sensitivity improvement by a factor 2-3 with respect to a
standard time-integrated point source search. The analysis has been done with
an unbinned method based on the minimization of a likelihood ratio applied to
data corresponding to a live time of 60 days. The width of the flaring periods
ranges from 1 to 20 days. Despite the fact that the most significant studied
source is compatible with background fluctuations, recently detected flares
promise interesting future analyse.
