This Web site has lots of information on the system, which is also known
as Almaaz:

http://www.hposoft.com/Astro/PEP/EpsilonAurigae.html

To quote:

"To try to unravel this system's mystery, a concentrated effort was undertaken during the 1982-1984 eclipse. Hundreds of astronomers, amateurs and professionals, from around the world, observed the eclipse. Space born satellites observed in the ultraviolet and infrared. Ground based observations were photometric, spectroscopic, and polarmetric. Photometric observations were made with UBV filters, narrow band filters, and at wavelengths into the far infrared."

And according to this entry in Wikipedia:

"In 2005, the system was observed in the ultraviolet spectrum by the Far Ultraviolet Spectroscopic Explorer (FUSE); as the star system was not emitting energy at rates characteristic of objects such as the neutron star binary system Circinus X-1 or black hole binary system Cygnus X-1, the object occupying the center of the disk is not expected to be anything of the sort; in contrast, a new hypothesis has suggested that the central object is actually a B5-type star."

Imagine what we will be able to do when the next eclipse period starts
in 2036. If Epsilon Aurigae were closer, I would even advocate it as one
of our first interstellar mission targets.