SIMBAD references

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.