2010CBET.2163....1M

G. H. Marion, Texas A&M University and University of Texas; J. Vinko, University of Szeged; and J. C. Wheeler, University of Texas, report that a spectrum of 2010U (cf. CBET 2161) was obtained on Feb. 7.3 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by M. Shetrone. The spectrum is dominated by a blue continuum with strong, narrow P-Cyg emission features of H I, Ca II, Na I, and possibly O I. The spectrum shows strong resemblance to those of luminous blue variable (LBV) outbursts ("supernova impostors"; e.g., Van Dyk et al. 2000, PASP 112, 1532; Smith et al. 2009, Ap.J. 697, L49). The absolute magnitude of the transient (using the host-galaxy distance of 3.3 Mpc from NED) is -11.7, which is typical for such events. The expansion velocity, calculated from the minimum of the narrow P-Cyg features, is about 900 km/s, which also supports the classification.