A very nice paper about eta Gem by Willy Torres at Harvard (and co-author Kristy Sakano) appeared this evening on astro-ph:
Eta Geminorum: An Eclipsing Semiregular Variable Star Orbited by a Companion Surrounded by an Extended Disc
...which leverages archival visual photometry and radial velocities extending back a century to show that this system is a long-period eclipsing binary of the epsilon Aurigae type. The earliest eclipse event witnessed is in re-reduced observations by Schoenfeld in 1874, which were recovered from the AAVSO database.
Thanks for the heads up Brian. I have not had the time to pick the analysis apart, but that really is a good paper. i am surprised they didn't use Harvard History department to search ancient civilization records.
I have been fascinated by the Visual-only observations of EM Cyg that show the eclipsing binary in the noise of the UGZ activity. The visual data is fairly consistent (with one recent exception) over 50 years. EM Cyg is almost 10 magnitudes dimmer than eta Gem. Perhaps there will be more papers about complex stellar systems based on old visual observations.