[IAUC] CBET 1251: 20080210 : BF CYGNI

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                                                  Electronic Telegram No. 1251
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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BF CYGNI
     U. Munari and A. Siviero, Istituto Nazionale di Astrofisica, Padova
Astronomical Observatory; and S. Dallaporta, P. Valisa, L. Buzzi, G. Dalla
Via, A. Maitan, L. Baldinelli, S. Moretti, S. Tomaselli, C. Gualdoni, and G.
Cherini, ANS ("Asiago Novae and Symbiotic stars") collaboration, write that
BF Cyg is currently on a rapid rise to a new bright maximum, as indicated by
the following magnitudes and colors:  Feb. 8.18 UT, B = 11.146, B-V = +0.76,
V-Ic = +1.52; Feb. 9.19, 11.086, +0.74, +1.51.  This symbiotic nova erupted
in 1894, peaking at B = 9.7 (Leibowitz and Formiggini 2006, MNRAS 366, 675),
and its decline back to quiescence required a century to complete.  In 2006,
Munari et al. discovered that BF Cyg was entering a new outburst phase (cf.
CBET 596), peaking at B = 10.28, U-B = -0.31, B-V = +0.47, V-I_c = +1.14,
and R_c-I_c = +0.59 on 2006 Oct. 12.  Since then, BF Cyg had been smoothly
declining, reaching B = 12.00, B-V = +0.81, V-I_c = +1.79 by 2007 Dec. 13.
The spectroscopic evolution following the 2006 outburst has been tediously
slow and characterized by persisting low-ionization conditions.  Spectra
obtained on 2007 Dec. 29 were still characterized by a forest of Fe II
emission lines accompanying Balmer and weak He I emission lines.  Spectra
for 2008 Feb. 10.18 surprisingly show only marginal changes, in spite of
the intervening large photometric brightening; they are still dominated by
the same Balmer, He I, and Fe II emission lines, with reduction of their
equivalent widths by about 20 percent compared to the spectra of Dec. 2007.


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                         (C) Copyright 2008 CBAT
2008 February 10                 (CBET 1251)              Daniel W. E. Green