Electronic Telegram No. 596
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
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BF CYGNI
     U. Munari and A. Siviero. Istituto Nazionale di Astrofisica, Padova
Astronomical Observatory; S. Moretti, M. Graziani, and S. Tomaselli,
Associazione Ravennate Astrofili Rheyta; and L. Baldinelli and A. Maitan,
Osservatorio Paolo Pizzinato, Bologna, write that the symbiotic nova BF
Cyg is on a rapid rise to a large-amplitude outburst.  It took a whole
century for BF Cyg to return toward quiescence following the outburst that
peaked at B = 9.7 in 1894 (Leibowitz and Formiggini 2006, MNRAS 366, 675).
The authors have tightly monitored the object as part of the ANS
Collaboration and have found the brightness of BF Cyg to be stable during
2006 around the mean values U = 11.64, B = 12.50, V = 11.84, R_c = 10.45,
I_c = 9.37.  However, on July 31 the star started brightening, slowly at
first and now much faster.  The last measured values are U = 9.69, B =
10.34, V = 9.89, R_c = 9.31, I_c = 8.63 on Aug. 14.94 UT, and V = 9.75, R_c
= 9.27, I_c = 8.59 on Aug. 15.86.  The last time that BF Cyg was seen this
bright in the blue was around 1925, during its decline from the 1898
eruption.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2006 CBAT
2006 August 18                   (CBET 596)               Daniel W. E. Green