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[vsnet-campaign 1304] RX J1643.7+3402 - a bright novalike CV showing a complex variety of periodicities
Dear colleagues,
RX J1643.7+3402 is a ROSAT X-ray source, that was discovered as a bright (V
~12.6) cataclysmic variable by A. Michaelian et al. (A&A 381, 894-904
(2002)). Michaelian reported spectroscopic and photometric observations,
showing it to be a novalike variable sharing some of the characteristics of
the SW Sex sub-class of novalike CVs. He announced a spectroscopic period of
either 2.575h or 2.885h, thus within the period "gap". He furthermore
reported a photometric modulation with a probable period of 2.595h and an
amplitude of ~0.1 mag in V.
I have started observing this interesting object on Apr 10, 2002 and since
then have accumulated over 6 nights of high-speed unfiltered CCD time series
photometry. I used the 0.35-m f/6.3 telescope and ST-7 CCD of CBA Belgium
Observatory. The light curves are available on my web site
(www.lunarpages.com/cbabelgium).
The object definitely is amongst the most interesting CV's I have ever
studied, showing a complex variety of periodicities. I'm still working on
the period analysis, and I'm switching over now to a new period
determination programme ("Period98", by M. Sperl), simply because the one I
was used to ("Period", by P. Wils), is less suited for handling this type of
complex data sets.
Over periods of 10 to 15 minutes, the object is showing light modulations as
large as 0.2 - 0.3 mag, repeating all night long at irregular intervals.
There's a superimposed, much longer term modulation, likely related (or
identical) to the photometric modulation reported by Michaelian.
With these 'credentials', the object deserves attention of all
'photometrists' out there. It's a bright object, so perfectly suited also
for small scopes and/or first time CCD photometrists !
Looking forward to hearing your results ...
Best regards,
Tonny Vanmunster
CBA Belgium Observatory
www.lunarpages.com/cbabelgium
vsnet-adm@kusastro.kyoto-u.ac.jp
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