[vsnet-alert 7622] GZ Cnc outburst: very strange light variation!

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

GZ Cnc outburst: very strange light variation!

   We have just received the fully analyzed data from Arto Oksanen
(the magnitude in the previous posting was unfiltered CCD magnitude on
a V-band comparison star).

   The data show very unusual light variations!  There are at least
three variation components.  1) slow fading, 2) slow modulations (full
amplitude 0.07 mag) with a period near the orbital period (the data are
not yet sufficient to tell between the orbital and superhump periods),
and 3) spiky, coherent-looking short-period oscillations.

   The coherent-looking short-period oscillations have amplitudes about
0.05 mag and periods close to 10-20 min.  The light behavior even reminds
me of an intermediate polar! (if this is the case, the suggestion
by Kato et al. (2002) A&A 396, 929 will be validated).  The light curve
also resembles that of V592 Cas last year (see Kato and Starkey (2002),
IBVS 5358).  The light variations alternatively look like super-QPOs
(Kato et al. (1992) PASJ 44, L215; see also Warner and Woudt (2002)
MNRAS 335, 84 for a further discussion; VSNET web page
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/DNe/superqpo.html ).

   These variations were not prominent in long time-series observation
on January 28.  In any case, the present observation clearly illustrates
the peculiarity of the outburst of GZ Cnc.  Please continue observing
the object!  The object has been intensively observed as a priority target
by the VSNET Collaboration for the past month; we will be able to draw
a more definitive conclusion with the newly available data during the
present outburst!

Regards,
Taichi Kato
VSNET Collaboration team

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