[vsnet-campaign 201] V803 Centauri

["William S G Walker" <astroman@voyager.co.nz>]

Greetings,

The bright outburst of V803 Cen more or less concluded on June 8. At that
stage the star was falling by two magnitudes per day and was at V = 16.0 on
June 9. I've attached light curves from Farm Cove (Jennie McCormick and
Fred Velthuis) and Wharemaru (Stan Walker) which illustrate the strongly
periodic 27 minute signal which is analagous to a superhump. 

It seems that the star may now have recovered to the bright level where it
cycles between 13.4 and 14.8 over a period of 22 to 24 hours. In 1999 and
2000 there were indications that this cycling period may have become even
shorter. So this would be a good project for visual observers to check,
mainly by making measures at intervals of about two hours on any clear
nights. It's not really possible for CCD observers to get enough time at
it. Of course, V803 may decide to go back to the fainter level of around
16-17 where it's no easy mark, even for CCD cameras.

The next bright outburst should be in mid-August. This gives us a 60 day
period to try to get a better handle on just what the present cycling
period is. If we can get measures from SA, Aust and NZ it should be simple
to get good periods. The cycling period seems to change from a shorter
length just after an outburst to longer as the next bright outburst
approaches. In the recent case, however, it was down at  = 16.5 on May 24
and 26, when I did a couple of CCD runs. Some structure, but hard to see in
the noise.

If each visual observer could get about 20 measures over this period it
would be great. Drop me a line if you're interested and send me a copy of
the measures at the end of June and July. The recent outburst was probably
the best observed yet. A good effort

Regards,
Stan

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