Circular No. 3345 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758 SS 433 B. Margon and colleagues, University of California at Los Angeles, report that the highly variable x-ray star SS 433 (cf. IAUC 3314) displays intense emission lines that change their wavelengths by enormous amounts, up to 1000 A in 50 days. These emissions have been unambiguously identified as two sets of Balmer and He I lines, one with large redshift and one with large blueshift, in addition to a stationary zero-velocity system. Liebert et al. (preprint submitted to Nature) have independently reached the same conclusion. Further analysis of nine months of data (many of them graciously provided by colleagues within the University of California system) now shows the line motions to recur with period 160 +/- 3 days or an integer multiple thereof. The periodicity appears in all available data and has therefore persisted for at least parts of 3 cycles. The two systems reached maximum positive and negative velocities of +50 000 and -30 000 km/s, respectively, on 1978 Nov. 12 +/- 3 - the exact epoch is ambiguous due to the flat-topped nature of the velocity curves - implying another expected maximum centered about 1979 Apr. 21 and persisting for about one week. Minimum velocities of +10 000 and 0 km/s have been observed in the red and blue systems thus far, but gaps in the data permit the minima to be deeper, and the two systems may conceivably reverse places in 1979 June, with the redshifted lines acquiring a blueshift and vice versa. Each of the moving systems normally exhibits broad H-alpha, H-beta, H-gamma and H-delta emissions, plus often weaker He I 5876 A. The behavior is so unprecedented that all spectroscopic observers are urged to obtain as many data as possible on the descending velocity curves in 1979 May and June. SUPERNOVA IN NGC 3913 F. Ciatti, S. Ortolani, P. Rafanelli and L. Rosino, Asiago Astrophysical Observatory, write: "Spectrograms were obtained with the 182-cm telescope on Mar. 27 and 30 and Apr. 1. The spectra show the characteristics of a type I supernova about 15 days after maximum, with the strong absorption feature at 6160 A and emission features at 4210, 4590, 4940, 5190, 5890 and 6320 A. It is very likely that the supernova attained a maximum of magnitude ~ 13 around Mar. 15. The supernova 1963J in the same galaxy attained magnitude 13.7 at maximum. Infrared and blue spectra of the new object taken after Apr. 1 are under reduction." 1979 April 18 (3345) Brian G. Marsden
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