CBA
Observations of Var Cam 06
Var Cam 06 was discovered as a new variable star by
Wolfgang Kloehr on 2006, Dec 16th at mag 15.2CR. It
is located at R.A. 05h57m18s and Decl. +68°32'26"
(J2000.0). Immediately following the discovery, the
CBA network started an intensive time-series CCD
photometry campaign.
We herewith report initial results of an analysis
of 4002 CBA time-series observations of Var Cam 06,
obtained by 7 observers of the CBA network (David
Boyd, Bob Koff, Dave Messier, Jerry Foote, Tonny
Vanmunster, Arto Oksanen and Pierre de Ponthiere).
Available data have been grouped in two datasets,
one covering the outburst interval between JD+
4087.0 and 4090.0, and another one covering the
interval between JD+ 4090.0 and 4096.0 (see fig. 1
and 2). We seem to have missed the initial phase of
the outburst - i.e. no early superhumps (or outburst
orbital humps) have been
observed.
Fig. 1 - Var Cam 06 CBA
observations between JD+ 4087.0 and
4090.0
Fig.
2 - Var Cam 06 CBA observations
between JD+ 4090.0 and 4096.0
The first dataset comprises the
common superhump stage of the outburst, and consists
of 1293 observations, covering a time span of 2.7
days. Using the ANOVA
period analysis method, we find a common
superhump period of 0.05339 +/- 0.00009 d, and an
average superhump amplitude of 0.18 mag. This stage
of the outburst is clearly dominated by a
single-peak signal (fig. 3 and 4). Note that the
superhump period value is extremely short, and
definitely amongst the shortest periods presently
known. ASAS 023322-1047.0, which went into outburst
early this year, has a slightly longer period of
0.056 d.
Fig.
3 - ANOVA period analysis for the
observations of fig 1
Fig.
4 - folded lightcurve for the
observations of fig 1 at Psh = 0.05339 d
A clear change in the superhump profile is noted
during the second stage of the outburst, which is
represented by 2709 CBA observations, obtained over
a period of 4.5 days. Using Peranso's ANOVA method,
we now find a (late) superhump period of 0.05338 +/
0.00006 d. The superhump signal is weaker (amplitude
of approx. 0.11 mag), has double-peaked humps, and -
more importantly - these humps are roughly
anti-phased (shifted in phase by ~180 degrees) with
the common superhumps, meaning that hump maxima now
occur where minima would be expected (fig 5 and 6).
The latter is a typical characteristic of late
superhumps.
Fig. 5
- ANOVA period analysis for the observations of fig 2
Fig. 6
- folded lightcurve for the observations of fig 2 at
Psh = 0.05338 d
The above findings clearly reveal the
SU UMa-type nature of this cataclysmic variable.
Based on recent observations (end of December 2006) of
VarCam06 submitted to the CBA, it seems this
interesting object is now returning to quiescence.
Keep on monitoring this target for echo outbursts.
Tonny Vanmunster
Joe Patterson
