• Filippenko, A. V.
• Munari, U.
• Zwitter, T.
• Li, W.

Abstract

W. Li and A. V. Filippenko, University of California, Berkeley; and S. D.Van Dyk, Infrared Processing and Analysis Center, California Institute ofTechnology, report that SN 2004et was imaged on Sept. 30 UT with the0.76-m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory,yielding position end figures 25s.37, 17".8 (equinox 2000.0; uncertaintyabout 0".2 in each coordinate).A faint object, possibly extended,appears at this location on multi-band images of NGC 6946 taken with theKitt Peak 0.9-m telescope on 1989 May 30.Based on calibrations of thefield on three photometric nights with the Lick Nickel 1-m telescope,they measure the object at R = 20.8 +/- 0.2, adding that it was notdetected in the Kitt Peak B- and I-band images (B 〉 21.3, I 〉 19.7).Using a distance of 5.5 Mpc to NGC 6946 (Shapley et al. 2001, Ap.J.Suppl. 137, 139), and E(B-V) = 0.41 mag (from Zwitter and Munari, above),the absolute magnitudes of the object are M_B 〉 -9.1, M_R = -8.9, and M_I〉 -9.7.The high luminosity makes it likely to be a star cluster ratherthan a single star.Unfortunately, there do not appear to be HubbleSpace Telescope or KAIT pre-explosion images of the site of SN 2004et.

Topics

• cluster
• nickel