[vsnet-alert 9415] Re: EK TrA: likely superhumps; post-superoutburst stage?

[Berto Monard]

Dear Taichi,

I could be wrong but the lightcurve does suggest a different behaviour
from that of other UGSU DNe. I would not be surprised that we are now
seeing a transition phase to a full outburst.
Last night's observations (16 July) show a clear brightening, perhaps
to a full outburst: anomalous behaviour? It is not clear where EK TrA
will eventually end up in the classification table.

Regards,

Berto Monard


>>> Taichi Kato <tkato at kusastro.kyoto-u.ac.jp> 17/07/2007 03:05 >>>
Berto Monard has reported six nights observations of EK TrA
(covering one night during outburst and five nights during
the post-outburst phase).  As already pointed out by Berto,
the light curve show significant modulations.
The analysis of the data has yielded a period of 0.06441(2) d.
This periodicity was strong on most nights (amplitudes 0.1-0.2
mag).  On July 11 and 12, the profile was double-humped,
resembling late-superhump stage of SU UMa-type superoutbursts.

   The orbital period (0.06288(5) d, Mennickent and Arenas 1998)
does not fit the variation.  The periodicity more implies
a superhump period with a normal fractional superhump excess
of 2.4%.

   Although first visual detection of this outburst was reported
on July 6 (P. F. Williams), the overall photometric behavior
suggests that the present outburst was a superoutburst
(early stage of the outburst missed or a relatively short
superoutburst?).  Observations (even negative) before July 6
would be helpful.