[IAUC] CBET 1504: 20080911 : CI CYGNI

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                                                  Electronic Telegram No. 1504
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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CI CYGNI
     U. Munari and A. Siviero, Astronomical Observatory of Padova, INAF;
and P. Valisa, P. Ochner, S. Dallaporta, A. Vagnozzi, S. Moretti, and S.
Tomaselli, Asiago Novae and Symbiotic Stars (ANS) collaboration, report
that absolutely fluxed optical spectra of the symbiotic star CI Cyg,
currently in outburst for the first time since 1975, were recorded at low
and medium resolution on Sept. 1.82, 2.81, and 8.85 UT with the Asiago 1.22-m
and Varese 0.60-m telescopes.  There have been five recorded outbursts of CI
Cyg, each one with its own unique development (sometimes quite complex with
several maxima and deep minima), and almost all have commenced slightly
before or during an eclipse of the outbursting white dwarf by the M4 III
companion, as in the current event.  The mean values obtained for CI Cyg
with various telescopes of the ANS collaboration between Sept. 8.8 and
9.9 are V = 9.63, B-V = +0.84, V-R_c = +1.01, and V-I_c = +2.30.  Compared
with the corresponding values for Sept. 1 reported on CBET 1487, CI Cyg is
currently experiencing a standstill phase, halfway from quiescence to
outburst peak.  These recent spectra of CI Cyg in outburst are radically
different from those of quiescence.  The blue continuum is much reinforced
and has appreciably veiled the TiO absorptions, with the Balmer discontinuity
now in strong emission.  All high-ionization emission lines are gone -- in
particular, [Ne V], [Fe VII], and He II.  Only Balmer and He I remain in
emission, with faint traces of both [O III] and [Ne III].  On Sept. 8.85,
the absolute fluxes of H_beta, He I 587.6-nm, [O III] 500.7-nm, and [Ne III]
396.7-nm are 15.2, 5.20, 1.76, and 1.44 10**(-11) erg cm**(-2) s**(-1),
respectively.  The flux of the H_beta and He I lines is about 1.5 times
larger than in quiescence, while that of [O III] and [Ne III] is
approximately similar.  The H_alpha profile displays an absorption component
superimposed on the emission component and blue-shifted by 40 km/s.  The
H_alpha:H_beta:H_gamma:H_delta flux ratio is 9.15:1.00:0.34:0.23.
     Visual magnitude estimate of CI Cyg by J. Carvajal, Madrid, Spain:
Aug. 31.956 UT, 10.2.


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                         (C) Copyright 2008 CBAT
2008 September 11                (CBET 1504)              Daniel W. E. Green