2008CBET.1504....1M

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:Hbeta:H_gamma:Hdelta flux ratio is 9.15:1.00:0.34:0.23.