2008CBET.1242....1B

S. Blondin, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that a spectrum (range 350-740 nm) of 2008U (cf. CBET 1238), obtained on Feb. 8.46 UT by M. Calkins with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be either a reddened type-IIn supernova or an outburst of a luminous blue variable (LBV). The spectrum consists of a reddened continuum and narrow Balmer emission lines (FWHM about 300 km/s), as well as other emission lines from the underlying host galaxy. The H_alpha emission line has a broader (FWHM about 3000 km/s) component not present in the other Balmer lines. While this may be the signature of a supernova-like event, adopting a recession velocity of 1948 km/s for the host galaxy (from The Updated Zwicky Catalog, http://tdc-www.harvard.edu/uzc/), and assuming no peculiar motion, the discovery magnitude of 18.4 corresponds to an absolute magnitude of roughly -15, which is more consistent with an LBV than a supernova (cf. also SN 1997bs: Van Dyk et al. 2000, PASP 112, 1532).