[vsnet-outburst 4874] Var73 Dra - analysis of the Dec 08-10 observations at CBA Belgium Observatory

["Tonny Vanmunster" <Tonny.Vanmunster@cbabelgium.com>]

Dear colleagues,

I have now made all of my Var73 Dra observations available at my web site,
showing the evolution of this object over the course of 3 nights (Dec 08/09,
09/10, 1O/11). Here are the results of my data analysis.

Over the 3 nights, I collected 390 observations of Var73 Dra. During the
first 2 nights, no clear hints of superhumps were present, and the average
amplitude of the light modulations was about 0.10 mag. This increased
considerably on December 10/11, at the moment superhumps started to appear.
The amplitude was now 0.21 mag.

On the basis of the December 10/11, 2002 observations, and using the PDM
method, I found a superhump period value of 0.1069 +/- 0.002 d (short time
basis).

Our observations thus confirm the superhump period value determined by the
Kyoto team during the October 2002 outburst of Var73 Dra, and the fact that
this is a dwarf nova IN the period gap.  In addition, our observations
establish the superoutburst nature of the present outburst, as was already
assumed from a set of CCD observations obtained by Donn Starkey one night
ago (see vsnet-superoutburst 1761).

More important is the conclusion that the supercycle of Var73 Dra is around
60 days, similar to ER UMa type dwarf novae. Var73 Dra therefore is the
first ER UMa type dwarf nova IN the period gap, confirming Taichi Kato's
assumption [vsnet-alert 7588].

Kind regards,
Tonny Vanmunster
CBA Belgium Observatory
email : Tonny.Vanmunster@cbabelgium.com
website : www.cbabelgium.com

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