CBA Belgium observations dd 2006, Jan 23/24

I started a time-series (unfiltered) CCD photometry session of this target on Jan 23.72 UT, using a 0.35-m f/6.3 telescope and ST-7XME camera at CBA Belgium Observatory. The session lasted for 3.6 hours, and shows the presence of a weak periodic signal, that might indicate the emergence of early superhumps, although still unsure at this moment. The linear trend of decline has been removed from the light curve below. 

 
A period analysis using Peranso's ANOVA method, yields a period of 0.055 +/- 0.005 d, with an amplitude of about 0.1 mag. If this signal relates to early superhumps, it would be amongst the shortest presently known. The object faded by approx. 0.04 mag over the course of my session. A period significance analysis, using a Fisher Randomization Test (with 200 Monte Carlo permutations), yields a false alarm probability close to 0%, hence indicating that the above signal is quite likely secure. 

 
CBA and AAVSO observations of the Early Superhump Stage

Following the above announcement, I received additional CCD observations of ASAS 023322-1047.0 from Tom Krajci, David Boyd, Berto Monard, Michael Armstrong, Tim Crawford and Diego Rodriguez Perez. Our dataset now comprises a total of 2222 observations, covering a time span of 5.8 days, i.e. the entire initial outburst stage.

A period analysis using the ANOVA method (Peranso) reveals a dominant signal at 0.05485 +/- 0.00026 d, that is clearly showing the signature of double-peaked "early superhumps". The average amplitude is just below 0.05 mag. I have created a phase diagram, folding all observations over the above mentioned period, and I then averaged the data per 10 observations. The resulting phase diagram is very nicely revealing the early superhump. Amazing to see how much detail we can derive by joining the observation sets of individual observers, taking into account that each session was relatively short.

 
The object meanwhile has entered a next outburst stage.