From jop at astro.columbia.edu Tue Apr 5 10:07:50 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 5 Apr 2005 10:07:50 -0400 (EDT) Subject: (cba:news) stars for april Message-ID: Dear CBAers, Plenty of activity in CBAland recently. The coverage on N Pyx 05 (actually a dwarf nova, name not yet assigned) has been excellent, but the star is now too faint for most of you - so I recommend you sweep it off the stage. The power spectra of the spliced shows not only the main superhump signal (at 15.94 c/d) but also the little fine-structure peaks separated by 0.28 c/d, which reveals the precession frequency. When we get coverage this good, we can usually measure nu-orb (in this case 15.94+0.28=16.22) even without waiting for observations at quiescence. Kudos to the usual Southern hotshots on this one: Berto, Jennie, Bob Rea, Tom Richards, Greg Bolt, Bill Allen, Alex Liu (though Alon Retter). Boreal regions have had a nice show too, courtesy of RX0532+62, another newly-popped-up dwarf nova. This one's pretty strange. We caught the "normal max" just prior to the supermax, and have now tracked it for 20 consecutive days. Superhumps started to develop on the declining branch of the normal max, which I think has never been seen before (though excuses could be found for it). The superhumps came on like gangbusters (American slang for "big and irresistible"), but have now - several mag below max - become hard to spot amid the very large rapid flickering in the star. Very annoying, this flickering... if we could find some pattern in it, it would be a fascinating thing to study - but so far I haven't managed to find anything. I'm inclined to suggest that we give up on this star; but it has tossed some surprises at us, and maybe has one more. If you're feeling lucky, keep it up! But my general feeling is that it's time for a major house cleaning. Delete YY Dra, N Pyx 05, and maybe RX0532+62. In the south, I recommend starting a campaign on CP Puppis - a famous old nova which we've never attacked in a serious way. Good target for the dark of the Moon. Later in the night, V391 Hya (a little brighter at 14.3) is a good target - we still haven't managed to find a period in this 14th mag novalike. I'm inclined, for the reasons stated by Berto yesterday, to regard the new star in Serpens as a likely nova, not dwarf nova - and hence not likely to be a good target for photometry now. I could be wrong in one or both of these... but that's my current feeling. ("Not good" basically means "unlikely to yield a periodic signal", by the way.) In the north, I recommend BK Lyn as primary campaign target, but also would love to see time series on RX0625+73 and BG CMi.\ joe From jop at astro.columbia.edu Fri Apr 22 10:12:07 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 22 Apr 2005 10:12:07 -0400 (EDT) Subject: (cba:news) stars for late april Message-ID: Dear CBAers, Time for major changes. In the south, we have enough now on CP Pup and V391 Hya - let's retire 'em for the season and see what the analysis brings. For this very bright week coming up, I recommend BRIGHT stars. 1. V395 Hya - at 13.3, probably bright enough to subdue moonlight. Still no Porb - or P(anything) - known in this novalike variable. 2. RW Sex. We've never done this star, and at 10.5 (or so) it's packed with photons (keep exposures short, or filter, or even defocus if necessary - to avoid aturation). We should, just to keep eyes reasonably trained on long-Porb stars as well. You should be able to get excellent data, and can laugh at the Moon. If you have filters, use a V. In the north, as I mentioned last night, GO Com is a tempting target, since it seems to superhumping strongly right now. RW Sex is available for us borealites too, since we still have no nodes in South America to carry the banner for our longitude. And there's CR Boo... it's definitely time to begin the year's campaign; I just dunno the brightness right now. If brighter than 14.5 or so, then I'd say: start now! Otherwise, need to wait for the Moon to move/fade. Whichever you choose, it is - as usual - highly desirable to revisit that target consistently in the nights to follow. That makes it possible to squeeze out a much more sensitive (and straightforward) periodicity search. Buena suerte! joe From jop at astro.columbia.edu Sat Apr 30 08:22:09 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 30 Apr 2005 08:22:09 -0400 (EDT) Subject: (cba:news) V504 Cen Message-ID: Dear CBAers, Of the southern persuasion, anyway. Berto has obtained a few runs on this little-studied novalike variable. It appears to have two periods present, and that makes it of very high interest to us... and very well placed to boot. This is definitely the top priority star in the southern sky right now! RW Sex had its proverbial day in the Sun. We have a pretty good limit now (<0.025 mag) now on orbital/superhump modulations. That's all the star is gonna give us! Message on northern stars later today. joe