[Aavso-photometry] More ASAS 023322-1047.0 CBA observations - weak signal confirmed

[Tonny Vanmunster]

Dear colleagues,

Next to Michael Armstrong's confirmation, I received further ASAS 023322 CBA
observations from Tom Krajci (through Joe Patterson). Combining his data
from last night, with mine of tonight (yielding a total of 629
observations), I now obtain a dominant period at 0.0548 +/- 0.0006 d, that
is clearly "above noise" level. The analysis was done using the ANOVA method
(Peranso) - by the way one of the best period analysis methods for
cataclysmic variable stars (and beyond ?). 

It seems quite evident that this signal corresponds to early superhumps,
that should become more prominent in the next days. Follow-up studies are
highly encouraged. I have a presentation tomorrow evening at a local
observatory, and therefore will not be able to cover ASAS 023322, but I'm
interested to learn about your observations.

Best regards,
Tonny

Tonny Vanmunster
CBA Belgium Observatory
http://www.cbabelgium.com 
 
PERANSO : The Light Curve and Period Analysis Software
http://www.peranso.com


-----Original Message-----
From: owner-cba-news at cba.phys.columbia.edu
[mailto:owner-cba-news at cba.phys.columbia.edu] On Behalf Of Tonny Vanmunster
Sent: Tuesday, January 24, 2006 12:28 AM
To: cba-news
Cc: cvnet-outburst at yahoogroups.com; 'Aavso-Photometry'
Subject: (cba:news) ASAS 023322-1047.0 - weak possibly periodic signal (2006
Jan 23/24, CBA Belgium Observatory)

Dear colleagues,

I started a time-series (unfiltered) CCD photometry session on ASAS
023322-1047.0, at Jan 23.72 UT, using a 0.35-m f/6.3 telescope and ST-7XME
camera of CBA Belgium Observatory. The session lasted for 3.6 hours, and
shows the presence of a weak possibly periodic signal, that *might* indicate
the emergence of early superhumps, although still very unsure at this
moment. The light curve has been made available at my website
http://www.cbabelgium.com, after having removed a linear trend of decline.
 
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. 

Evidently, follow-up observations are required over the next nights to
further study the behaviour of this variable and to determine its precise
nature. 
More details about my session are available at my website.

Kind regards,
Tonny


Tonny Vanmunster
CBA Belgium Observatory
http://www.cbabelgium.com 
 
PERANSO : The Light Curve and Period Analysis Software
http://www.peranso.com



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