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Circular No. 8414 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304 Phone 617-495-7440/7244/7444 (for emergency use only) SUPERNOVAE 2004es AND 2004et A. V. Filippenko and R. J. Foley, University of California at Berkeley (UCB), report that inspection of CCD spectra (range 330- 1000 nm), obtained by T. Treu and M. A. Malkan on Oct. 1 UT with the Shane 3-m reflector at Lick Observatory, reveals that SN 2004es (IAUC 8412) is of type II, perhaps 1-2 months past maximum brightness. The H_alpha line has little or no absorption component, but the emission component is strong and broad. Na I D and some Fe II lines have P-Cyg profiles. SN 2004et (IAUC 8413) is also of type II, confirming the classification derived from the high- resolution spectrum reported on IAUC 8413. The P-Cyg profile of H_alpha is greatly dominated by the emission component, but the other hydrogen Balmer lines have more typical P-Cyg profiles. The continuum is quite blue, although it plummets shortward of 400 nm. Narrow interstellar Na I D and Ca II H and K absorption lines are prominent. W. Li and A. V. Filippenko, UCB; S. D. Van Dyk, Spitzer Science Center, California Institute of Technology; and J.-C. Cuillandre, Canada-France-Hawaii Telescope (CFHT) Corporation, report that their analysis of deep, high-quality (seeing 0".8) images of NGC 6946, taken with the 3.6-m CFHT on 2002 Aug. 6 UT, shows a possible progenitor for SN 2004et consistent in position with the more blurred, blended object previously found in lower- quality images (seeing 2".7; IAUC 8413) -- located at R.A. = 20h35m25s.41, Decl. = +60o07'18".1 (equinox 2000.0; uncertainty about 0".2 in each coordinate), within 0".3 of the position of SN 2004et measured from KAIT images (IAUC 8413), with magnitudes B = 23.84 +/- 0.22, V = 22.83 +/- 0.26, and R = 22.31 +/- 0.18. Using the same distance and reddening estimates to SN 2004et (cf. IAUC 8413), the possible progenitor has M(B) = -6.5, M(V) = -7.1, and M(R) = -7.4, which may be consistent with a massive supergiant, although likely too bright and too blue for a single red supergiant. However, with ground-based data it is difficult or impossible to determine accurately the exact properties of the progenitor, given its probable membership in a compact association. Note that both the distance and reddening to SN 2004et may have substantial uncertainties. COMET 160P/2004 NL_21 (LINEAR) Following the identification by M. Meyer (cf. MPEC 2004-S18) of 1996 observations of comet P/2004 NL_21 (cf. IAUC 8408), on exposures taken via NEAT at Haleakala, the comet has received the permanent number 160P (cf. MPC 52734, 52764, 52766). (C) Copyright 2004 CBAT 2004 October 3 (8414) Daniel W. E. Green
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