2011CBET.2754....2B

J. M. Silverman, S. B. Cenko, P. E. Nugent, and A. V. Filippenko, University of California, Berkeley, report that inspection of a CCD spectrum (range 340-1000 nm), obtained on June 29 UT with the 10-m Keck I telescope (+ LRIS), shows that PSN J17592296+0617267 very closely resembles SN 2008S at early phases (Smith et al. 2009, Ap.J. 697, L49). Strong, intermediate-width (FWHM roughly 1000 km/s) hydrogen Balmer and Ca II near-infrared triplet emission lines are superposed on a relatively featureless continuum, and there are very narrow (unresolved) prominent [Ca II] emission lines as well. Thus, this object is most likely a "supernova impostor" resembling a type-IIn supernova, but resulting from the outburst of a luminous blue variable star. Note that the Ca II H and K absorption lines are extremely strong, yet Na I D absorption is weak, suggesting that the Ca II lines are of circumstellar origin and may well be variable; further spectroscopic monitoring is encouraged.