Epsilon Aurigae (eps Aur hereafter) is a single line spectroscopic eclipsing binary star system on which I did my Ph.D. dissertation research. The system is thought to be composed of an F-type supergiant and a B-type companion surrounded by a disk of opaque material of unknown composition.

Although this system is bright (V = 3.0) and has been known since antiquity, it did not receive much attention until it was discovered to have dimmed by nearly 50% in 1821. Since then, photometric and spectroscopic monitoring have revealed that the system is a eclipsing binary with a 27.1 year orbit. The system is classified as SB1 (single line spectroscopic binary) because only one of stars in the system is detectable.

In 1912 Henry Norris Russel published the first analytic methods for binary star analysis and applied it to epsilon Aurigae. The result was quite interesting: the system should be composed of two nearly equal mass stars, but yet only one was visible. Several theories were proposed to explain this perplexing result, but it was not until 1965 that Su-Shu Huang proposed that the other star may not be visible because it was surrounded by a disk of opaque material.

During the 1983 and 2009 eclipses observation campaigns were organized and data collected. Many of the results are summarized in subsequent publications which can be found on ADS. In particular, the 1985 eclipse has conference proceedings. The 2009 eclipse has a special edition of the JAAVSO.

The 2009-2011 eclipse also featured a website which was operated by Jeffrey Hopkins until late 2012 when he transfered the contents to me. The content of this directory largely originates from the original campaign website with some modifications and updates as needed.