[vsnet-alert 169] V1028 Cyg: detection of low amplitude su

[Taichi Kato <SDI00707@niftyserve.or.jp>]

   We have obtained five hours' continuous good quality CCD V-band light
curve of V1028 Cyg this night.  The light curve shows a very low amplitude
(0.04 mag and 0.03 mag, alternately) double wave.  A preliminary period
analysis gives the best estimate of the period of 0.0740 +/- 0.0010 day
(assuming the double wave; the value still preliminary).  Such amplitude
and profile are rather commonly exist in the earliest stage of super-
outbursts of WZ Sge-type dwarf novae (see AL Com posters presented by
several authors; AL Com: Kato et al. 1995 PASJ submitted; other example
can be found in HV Vir).
   Thus the present finding strongly support that V1028 Cyg belongs to
SU UMa-type dwarf nova which was observed during its earliest stage of
a superoutburst.  We expect in a few days the growth of tidal instability
will give rise to "usual" superhumps.  Since this "early superhumps" have
not been well understood, intensive and continuous onservations are highly
recommended, esp. in order to compare the period with the orbital one and
the ones expected to appear later.

   Congratulations and special thanks to J. Pietz for timely detecting this
rare event and sending the alert!  Also congratulations to keen AAVSO
observers who followed the rise!

Regards,
Taichi Kato & Ouda team

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