The gathering storm...
Observers are beginning to report a sea change. Totality is upon us and the center of the dark turbulent disk is just about to make its presence felt atop the beacon of light that is the F star in epsilon Aurigae.
Photometrically, bumps and wiggles have persisted, a mix of out of eclipse variations and the stately progression of the eclipse itself.
Spectroscopically, the enhanced absorption of shell lines has been waxing and waning as though disk substructure is coming increasingly into view. What we've been seeing is the "morning side" of the disk - the portion that has been facing cold space and is just starting to rotate toward the hot glare of the F star (7750K). As soon as we reduce this week's IRTF spectra, we'll share any info about changes detected in the near-infrared.
And soon, the fabled central opening. Thanks to some superb reporting by Swedish observers, one of the better documentation sets (attached file) suggests that within 2 or 3 months of 2nd contact, we could begin seeing central brightening. Observers at high latitudes and high altitudes stand the best chance to watch for this during summer.
And, ahoy, on the heels of the central clearing, comes the "evening side" of the disk - the portion that has been baked by F star light, toasted and coming into view during second half of totality (Aug2010-Mar2011). Last eclipse, this is when we saw the appearance of infrared CO features - the same as are seen in comets when they approach the sun and their icy coat sublimates.
The fun continues!
An additional info source you might find helpful is:
Keep reporting your visual estimates here! Many thanks.