The start of mid-eclipse brightening?

During the past week, careful observers have been struggling with the low horizon angle presented by epsilon Aurigae and its friends, due to approaching solar conjunction in early June.  Despite this, credible reports are being received that epsilon Aurigae may be as much as 0.1 mag brighter than it was during early May.  If you have a clear NW horizon and patience, try finding The Kids below Capella after sunset, and see if you can provide a brightness estimate during these challenging weeks of late spring.

The structure of the inner disk of epsilon Aurigae is one of the remaining big challenges this eclipse cycle.  Clear indication of mid-eclipse brightening will strengthen past claims for its existence.  If we are fortunate enough to get additional interferometric images as early as mid-August, perhaps that will show the degree to which the disk center is cleared of obscuring dust due to the ultraviolet radiation source thought to be lurking therein.  Spectroscopic observers have been reporting increases in the absorption strength of H-alpha and other lines, suggestive of a region entering the line of sight view toward the F star that is more ionized.  Lately, even the long standing emission features in H-alpha have been eroded - see attached example by Stan Gorodenski.

A good discussion of the central clearing effect on light curves can be found in open literature source: http://adsabs.harvard.edu/abs/1989SSRv...50..336C .

A useful discussion of the hot B5V star thought to exist at the center of the dark disk is detailed in open literature source: http://arxiv.org/pdf/1003.3694v1 .

Reports on the light curve thus far, and mid-eclipse reports can be found at:
http://arxiv.org/pdf/1005.3738 and
http://www.hposoft.com/EAur09/EAUR%20pdfs/SAS2010.PDF .

To recap: central clearing - if starting in May, with mid-eclipse in August, means indicators will persist into October/November 2010.  Thus, even if you can't find epsilon Aurigae lately due to sun angles, once it returns in late summer mornings, you should be able to judge whether a couple of tenths of magnitude brightening is still underway.

For that matter, the balance of totality has been "lumpy" in past eclipses too - so the fun should continue throughout the entire fall/winter observing season to come!