[vsnet-alert 12492] Re: [vsnet-outburst 11923] On the past standstills of WW Cet

Mike Simonsen mikesimonsen at mindspring.com
Mon Dec 13 14:35:28 JST 2010

The AAVSO light curves for the 1991 and 1992 observing seasons are visible here:

There is no obvious standstill in the data for either year. In 1991
(left) the October outburst is clearly visible, but WW Ceti continues
to vary between 12.0 and 14.0 afterwards. In 1992 (right), there is a
slight gap in the regular outburst cycle, but nothing resembling a

Admittedly, there is the hint of a standstill that may have occurred
during the seasonal gap, but the data does not meet the standards of
proof we have established for membership in the Z Cam classification.

The current standstill is undeniably more obvious, prolonged and
pronounced than any of the prior circumstantial evidence. And the
current standstill continues, now going on 90 days.

Mike Simonsen
Membership Director/Development Officer
American Association of Variable Star Observers

One Hundred Years of Citizen Science
********* AAVSO (1911-2011) *********

On Sun, Dec 12, 2010 at 8:36 PM, Taichi Kato
<tkato at kusastro.kyoto-u.ac.jp> wrote:
>   In relation to this,
> http://arxiv.org/abs/1012.1545
> "The First Historical Standstill of WW Ceti"
>   Although it was not documented nor particularly shown in the light curve,
> the first likely indication of a standstill in this system was noted
> in 1991 November by M. Iida, who noticed that the star remained at
> intermediate brightness at 12.4-13.0 following an outburst in October.
> The phenomenon was confirmed by three experienced observers, the others
> being M. Koshiro and M. Moriyama.  An inspection of the AAVSO data also
> confirmed the finding.  It was during the early ages of internet, and
> I'm not sure whether this phenomenon was communicated (e-mails not stored).
> There was a similar, but less marked, phenomenon in 1992 September,
> when there were several reports on this "standstill" or "unusual behavior"
> in the pre-VSNET circulation and CV circulars issued internationally
> by the VSOLJ team.
> It was a surprise to find Kiyota-san already recorded this phenomenon
> with a CCD camera!

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