2010CBET.2292....2E

N. Elias-Rosa, J. C. Mauerhan, and S. D. Van Dyk, Spitzer Science Center, California Institute of Technology, report that inspection of a spectrogram (range 400-860 nm) of 2010da, obtained on May 25.4 UT with the SOAR 4.1-m telescope (+ Goodman spectrograph), shows it to be a young "supernova impostor" in outburst. Assuming a recession velocity of 144 km/s (Lauberts and Valentijn 1989, Garching: European Southern Observatory; via NED) for the host galaxy, the "GELATO" spectrum-comparison code (Harutyunyan et al. 2008, A.Ap. 488, 383; available at https://gelato.tng.iac.es) provides good fits to spectra of "supernova impostor" 1997bs (Van Dyk et al. 2000, PASP 112, 1532) at several days after outburst. The blue continuum is dominated by strong, narrow H-alpha emission, with a no presence of a P-Cyg profile. There are also present other narrow Balmer lines, as well as lines of [N II], Fe II, He I (at about 587.6 and 706.7 nm, with some possible contribution from Na I D at about 589 nm), possibly a weak [He II] 468.6-nmline, and the [Ca II] near-infrared triplet.