2004IAUC.8296....3R

M. Riello, S. Benetti, E. Cappellaro, F. Patat, M. T. Botticella, G. Altavilla, A. Pastorello, M. Turatto, and S. Valenti report the discovery of six supernovae on CCD frames taken on Feb. 18 during a search performed with the Max-Planck-Institut 2.2-m telescope (+ Wide Field Imager) at the European Southern Observatory (ESO). SN R.A. (2000.0) Decl. V Offset z Type 2004ae 4 28 17.89 -36 18 55.0 23.3 < 0'.3 0.480 II 2004af 5 38 03.91 -23 59 00.2 22.5 3'.2 W, 4'.3 S 0.056 Ic 2004ag 9 51 01.49 -20 50 37.5 23.0 < 0'.5 0.362 II 2004ah 10 45 47.41 - 0 06 58.1 23.3 < 0'.8 0.480 Ia 2004ai 13 54 26.09 -12 41 15.9 23.4 1'.0 S 0.590 Ic 2004aj 14 20 37.58 -12 24 14.4 22.3 0.247 Ia Nothing was visible at the above positions on reference images taken during 2001-2002. Spectroscopy (range 600-1100 nm), obtained on Feb. 26 and 27 with the ESO 8.2-m YEPUN telescope (+ FORS2), reveals that each supernova was caught around maximum, with the exception of 2004af, which shows very strong nebular emission lines of Mg I], Na I, [O I], [Ca II], and Ca II, and 2004af bears a strong resemblance with that of SN 1998bw at about 6 months past maximum light (Patat et al. 2001, Ap.J. 555, 900). The enhanced emission that is observed in the range 400-550 nm may also be attributed to a blend of Fe lines. The absolute magnitude of 2004af, M(R) = -14.3 (H_o = 72 km/s/Mpc), is unusually bright for a type-Ib/c event at these phases and implies a maximum brightness M(R) < -19. This, coupled with the spectral appearance, make 2004af a hypernova candidate.