[vsnet-alert 6657] WZ Sge: giant humps and sharp eclipses!!

[Taichi Kato <tkato>]

WZ Sge: giant humps and sharp eclipses!!

Dear Colleagues,

   We have received new data from J. Pietz and A. Oksanen.  We have also
partially analyzed the data taken at Kyoto (two nights).  The direct
comparison between different observatories have become more difficult,
likely because of the different contribution of the companion star
[Unless you use PSF photometry, please don't try to correct the effect
of the contribution, and consistently use the technique you are most
familiar with; we would be also glad to receive raw images (raw images
should be directed to Ishioka-san, if you are going to send them to us)].

   Nevertheless, we have confirmed that the slowly fading trend continues.

   The most striking change is the appearance of high-amplitude humps
and sharp, clear eclipses on Sep. 17 data.  The light curve is similar
(but has even higher amplitudes) to that on Sep. 11, at minimum preceding
the 12th rebrightening.  It may be either that the "beat period" has
shortened to 6 d (possibly related to the recent period chnage?), or that
we are witnessing the increased hump activity before the next rebrightening
(if any).  Only observations can tell the truth!  Please continue the
present excellent coverage!!

   The light curve is placed on the VSNET WZ Sge page.

   The clear appearance of eclipses, and the changing humps strongly
suggest that substantial light is from the accretion disk even at this
moment, and the disk has a vigorously changing structure or geometry!

Regards,
Taichi Kato
VSNET Collaboration team

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