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While SN impostors resemble the Great Eruption of eta Car in the sense thattheir spectra show narrow H lines and they have typical peak absolutemagnitudes of -13 to -14 mag, most extragalactic events observed so far arequite different from eta Car in duration. Their bright phases typically lastfor 100~d or less, rather than persisting for several years. The transientobject UGC2773-OT had a similar peak absolute magnitude to other SN impostors,but with a gradual 5-yr prediscovery rise. In the 6 yr since discovery, it hasfaded very slowly (0.26 mag/yr). Overall, we suggest that its decade-longeruption is so far the best known analog of eta Car's 19th century eruption. Wediscuss extensive spectroscopy of the ongoing eruption. The spectra showinteresting changes in velocity and line shape that we discuss in detail,including an asymmetric Halpha emission line that we show is consistent withthe ejection of a bipolar nebula that could be very much like the Homunculus ofeta Car. Moreover, changes in the line width, line profile, blue excessemission resembling that of Type IIn supernovae, and the intensity of Halphasuggest the presence of strong circumstellar interaction in the eruption atlate times. This supports the hypothesis that the extended plateau of eta Car'seruption may have been powered by shock interaction as well. One interestingdifference compared to eta Car, however, is that UGC2773-OT so far does notexhibit the repeated brief spikes in luminosity that have been associated withbinary periastron events.

The Persistent Eruption of UGC~2773-OT: Finally, a Decade-Long Extragalactic Eta Carinae Analog