SIMBAD references

A. V. Filippenko, M. Ganeshalingam, and B. J. Swift, University of California, Berkeley, write: "Inspection of CCD spectra (range 330-1000 nm), obtained on Sept. 24 UT with the Shane 3-m reflector at Lick Observatory, reveals that SN 2004em (IAUC 8406) is of type II, shortly after the explosion. The object has a blue, nearly featureless continuum and clear hydrogen Balmer lines with P-Cyg profiles, but the emission component of H_alpha is considerably stronger than the absorption component. Weak He I 587.6-nm absorption is visible, as well. SN 2004en (IAUC 8406) is also of type II, but somewhat older, perhaps a few weeks after the explosion. SN 2004du (IAUC 8387) appears to be a normal type-II-P supernova with typical P-Cyg profiles; the narrow H_alpha emission line responsible for the previous classification of type IIn (IAUC 8388) was based partly on a superposed H II region. We confirm the suggestion that SN 2004ek (IAUC 8405) is a young type-II supernova with a blue continuum (IAUC 8409), but now the flux density shortward of 400 nm drops substantially. There are weak hydrogen Balmer and Fe II absorption lines, although the weak H_alpha line is almost entirely in emission."