2005IAUC.8521....2W

L. Wang, Lawrence Berkeley National Laboratory; and D. Baade, European Southern Observatory (ESO), on behalf of the collaboration on supernova polarimetry program, report that the type-Ic supernova 2005bf (IAUC 8507, 8520) was observed at the ESO's Very Large Telescope (+ FORS1; range 323-840 nm; resolution 0.26 nm/pixel) in polarimetry mode on Apr. 30. Preliminary inspection of the spectra indicates a transition to a type II-or type-Ib supernova. Assuming a recession velocity for the host galaxy of 5670 km/s (Falco et al. 1999, PASP 111, 438), conspicuous lines from He I 501.6-, 587.6-, 667.8-, and 706.5-nm are observed at velocities around 6200 km/s. The observations also show strong lines of Ca II H and K and the Ca II infrared triplet at velocities around 10000 km/s. An absorption line is detected at 624.8 nm – which, if identified with the Si II 635.5-nm line, gives an expansion velocity of about 5000 km/s; the same line, however, can be identified as H_alpha at a velocity of 14400 km/s. Similarly, absorption features are observed at 413.9 and 463.4 nm, which can be identified with H_gamma and H_beta, respectively, at a velocity of 14000 km/s. A blend of Fe II 516.0- nm and Fe III 515.6-nm is also present in the spectra, at velocity around 5200 km/s. The supernova shows polarized spectral features in excess of 2 percent across some spectral lines. Observations at all wavelengths are strongly encouraged.