Circular No. 3518 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 CI CYGNI R. Viotti, A. Giangrande, A. Altamore, G. B. Baratta, A. Cassatella, D. Ponz, M. Friedjung and G. Muratorio, Laboratorio di Astrofisica Spaziale, Osservatorio Astronomico di Roma, E.S.A. Villafranca, and Observatoire de Marseille, Communicate: "CI Cyg was observed with IUE at the mid-1980 eclipse (June 10) and just after eclipse (Aug. 29), when symbiotic activity was lower than dllring our previous IUE observation on 1979 June 11. We found that during the eclipse the continuum and intercombination lines were much weaker. After the eclipse the intercombination-line fluxes were still 30 percent smaller than in 1979. O I 130.2 nm was much fainter in 1980, while the Mg II 280-nm doublet had disappeared in 1980 Aug. Other permitted lines show smaller changes. Simultaneous optical spectra obtained at Campo Imperatore and Haute Provence Observatories indicate that H-alpha faded during minimum, while the H-gamma/O III 436.3-nm flux ratio had reversed during eclipse. The red spectrum of CI Cyg is now very similar to that of Z And. We conclude that emission lines are formed in different regions that were eclipsed to different extents." X-RAY EMISSION FROM LSI+61 303 G. F. Bignami and P. A. Caraveo, Istituto di Fisica Cosmica, Milan; R. C. Lamb, Iowa State University; and T. H. Markert, Massachusetts Institute of Technology, report the preliminary results of an observation with the Einstein Observatory of the field containing LSI+61 303, a radio star with a period of 26.45 days (cf. IAUC 3164, 3170, 3180, 3210 and 3464). The observation was performed with the IPC instrument on 1979 Feb. 3 for a total of ~ 830 s useful time. A clear point source (~ 60 counts over a background of 6) was detected with a best position at R.A. = 2h36m42s, Decl. = +61o01'20" (equinox 1950.0) and an estimated error-circle radius of ~ 1'. The energy flux from 0.2 to 4.5 keV is ~ 2.3 x 10-**19 J/s. The positional agreement with LSI+61 303 (the brightest object in the error circle) is good. Further Einstein observations recently obtained with the HRI instrument will be used to reduce the positional uncertainty to a few seconds of arc. The reported observation is part of a survey conducted with the Einstein Observatory of the error circles of selected gamma-ray sources seen above 100 MeV. LSI+61 303 lies within the 1o-radius error circle of CG 135+01 and may be causally related to it. 1980 September 26 (3518) Brian G. Marsden
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