2006CBET..421....1L

J. T. Lauroesch, Northwestern University; A. P. S. Crotts, Columbia University; J. Meiring and V. P. Kulkarni, University of South Carolina; D. M. Meyer, Northwestern University; and D. E. Welty and D. G. York, University of Chicago, report that high-resolution spectrograms of SN 2006X (cf. 8667, 8680), obtained with the Magellan Clay Telescope (+ MIKE spectrograph) on Feb. 13.35 and 23.25 UT, show unusually strong redshifted CN B-X (0,0) violet band absorption consistent with an origin in the interstellar gas in NGC 4321 (= M100). A preliminary analysis of these data yields an extraordinarily large equivalent width (0.0090 ± 0.0010 nm) for the CN R(0) 387.46-nm line, the EW being greater than published observations of this line through any Galactic interstellar cloud (e.g., Crutcher 1985 Ap.J. 288, 604; Roth and Meyer 1995, Ap.J. 441, 129; Pan et al. 2004, Ap.J. Suppl. 151, 313). Sightlines in our Galaxy with similarly large CN columns (e.g., HD 29647; Crutcher 1985) have visual extinctions (A_V) greater than 3 magnitudes. Other interstellar lines detected in M100 include strong saturated lines of Na I, Ca II, and K I, as well as modest absorption due to CH, CH+, and several diffuse interstellar bands.