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. +6832'26" (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

Fig. 1 - Var Cam 06 CBA observations between JD+ 4087.0 and 4090.0  

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.

3 - ANOVA period analysis for the observations of fig 1

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





Copyright © 2006 - Tonny Vanmunster.