The bright optical companion to the eclipsing millisecond pulsar in NGC 6397

We report the optical identification of the companion to the eclipsing millisecond pulsar PSR J1740-5340 in the globular cluster NGC 6397. A bright variable star with an anomalous red color and optical variability (similar to0.2 mag) that nicely correlates to the orbital period of the pulsar (similar to1.35 days) has been found close to the pulsar position. The peculiar shape of the optical light curves is unprecedented for a millisecond pulsar companion and is a clear signature of tidal distortions.