Central Bureau for Astronomical Telegrams
IAUC 3518: CI Cyg; X-RAY EMISSION FROM LSI+61 303
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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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