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(cba:news) CP Puppis, mostly (Joe Patterson) [2013-01-29T00:43:58Z]


Dear CBAers,

There sure a lot of great stars out there for our purposes - OT1126+08, SSS1222-31, and Nova Mon 2012... all rather unusual - borderline mysterious - stars executing nice periodic signals. Keep up the great work!

To my delight, Berto Monard and Bob Rea have taken me up on my suggestion of CP Pup. Their data shows big periodic humps near 90 minutes - but amazingly (to me) they just don't clearly define a period. I've never seen anything quite like it. Even if you fit the data with the most complicated thing I can easily imagine (roughly equal contributions from orbit, positive superhump, and negative superhump), it still doesn't fit. Accretion disk weather!

The best way out of this is to get the densest possible light curve. There's a lot of water in the southern heminphere, so it won't be easy. But if we could get South America (Arto? Josch?) on this star, and also western Australia (Greg), we could nearly track it around the clock. Jan-Feb is certainly CP Pup season. Pretty please?

I'm suggesting holding your fire re T Pyx for a couple more weeks. We definitely want another salvo of data from it later in the observing season (about a month hence), which will nicely constrain whether the new (post-outburst) period is evolving or constant.

No changes in the northern menu. For those of you doing RX0704+26 = V418 Gem, I strongly recommend a *short* integration time, which you really need to properly resolve the strong 240 s pulse. Most observers think they need to go long for this star - because it's faint (~17.4), and because the light curve *looks* very noisy. But it's likely that most of what you see as noise is actually pulse amplitude (!) So send me that noisy light curve - and if you take a power spectrum, you should see that 240 s signal easily. (It's listed as 480 s, but apparently the star has two active poles, because nearly all the power is at 240).

joe