NGC 2419, one of the brightest and most distant clusters in
the MW halo, is a metal poor Oosterhoff type II system suspected to be the relic
of an extragalactic system accreted by the MW.
Using deep 
, 
, 
time-series CCD photometry over about 10 years,
we have identified 101 variable stars in NGC 2419, of which 60 are new discoveries,
doubling the known RR Lyrae stars and detecting for the first time SX Phoenicis
stars (Ripepi et al. 2007). A paper presenting the catalogue of light
curves and the distance to the cluster derived with different techniques based on the
various variable stars detected in NGC 2419 is in an advanced stage of
preparation (Di Crescienzo et al. 2009).
This work is in collaboration with M. Marconi, I. Musella, V. Ripepi, M. Dall'Ora (INAF-Napoli Obs.), R. Di Crescienzo (INAF-Roma Obs.), L. Di Fabrizio (INAF-TNG), C. Greco (UniGe). This research was partly supported by MIUR-PRIN04 grant n. CRA 1.06.02.03 and by PRIN-INAF06 grant n. CRA 1.06.09.15.