"Third contact" is near.
Observers are reporting a slight increase in brightness during these final 2 weeks until PREDICTED "third contact" (March 19, 2011) - signaling the end of total phase of this long, long eclipse.
When two spherical stars of unequal size eclipse, there is a moment when one star is inside but in tangential contact - like the end of a total lunar eclipse, when the moon emerges from the darker part (umbra) of the earth's shadow. We can this moment the Third Contact - see attached figure.
However, epsilon Aurigae differs from the classical model in at least 2 respects:
1. the two "stars" aren't simple spheres - the eclipser is an elongated disk, and,
2. egress seems to happen twice as fast as ingress.
In terms of the first point, geometrical models are needed to derive when the equivalent of 3rd contact occurs - the eclipser profile against the F star changes shape, rounding out the inside corner of the light curve at 2nd and 3rd contacts.
In terms of ingress and egress rates, last time around these were: 115 days in decline from V=3.0 mag to V=3.8 in totality, but only 50 days for increase from V=3.8 back to V=3.0. Next blog, I'll explain how this might be interpreted.
Meanwhile, get outside in these spring evenings to watch the return of the light!