SN 2010da is a SN ``impostor"
ATel #2636; N. Elias-Rosa, J. C. Mauerhan and S. D. Van Dyk (Spitzer Science Center/Caltech)
on 25 May 2010; 18:46 UT
Credential Certification: Schuyler D. Van Dyk (email@example.com)
Subjects: Optical, Supernovae, Transient
We report that the inspection of a (range 400-860 nm) of 2010da (cf. CBET 2289) in NGC 300, obtained on May 25.4 UT with the SOAR 4.1 m telescope (+Goodman spectrograph), shows it to be a young SN ``impostor'' in outburst. Assuming a recession velocity of 144 km/s (Lauberts & 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 SN 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, atop an intermediate-width base (~1000 km/s FWHM), with a no presence of a P Cygni profile. There are also present other narrow Balmer lines, as well as lines of [N II], Fe II, He I (at ~5876 and 7067 A, with some possible contribution from Na I D at ~5890 A), possibly a weak [He II] 4686 A line and the [Ca II] near-IR triplet.