From jop at astro.columbia.edu Tue Dec 3 13:39:10 2002 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 3 Dec 2002 13:39:10 -0500 (EST) Subject: (cba:news) No turkeys on the menu! Message-ID: Definitely not. The campaign on Tau 2 is starting to yield its result. Our coverage is still dominated by USA longitudes (Dave S, Jerry F, Cap'n Bob, David Messier), but some contributions have come in from Bob Rea and Tonny (NZ and Belgium). So we've overcome simple aliasing, though the domination by one longitude still inflicts avoidable noise on the power spectrum. Anyway, the main story seems to be this: three signals in the power spectrum, a positive superhump at Po+3.4%, a negative superhump at Po-2.7%, and the nodal signal itself at 6 days. Cute! And damned interesting... at this Po, the positive superhump is expected at about Po+8%, so this implies a low mass ratio - which we can maybe make hay of. (Where did that expression come from, anyway?) We have to sharpen accuracy, and also explore the higher harmonics, which are still a bit weak. We have about 12 more days before the Moon will interrupt us - let's try to get tree-to-tree coverage until then. Especially those treasured and exotic longitudes oh-so-far from 90 degrees west! The other great star is EC0422-20. This one is *really* easy to do - very attractive target for small scopes, even if the declination is a trifle unappealing. For this one, our dominant coverage is from Berto and Greg Bolt (Pretoria and Perth), so our more common artillery in the USA and NZ haven't yet arrived in force - except for Lew Cook, whose data breaks the cycle-count logjam. The star shows BIG-TIME negative superhumps at 3.32 hours. Those are the two CBA targets for the south. For the north too - in a full display of hemispheric brotherhood I hope. But we get some extra hours of darkness in the north. I recommend short (1-2 hr) observations of FO Aqr and AO Psc if you'd like an early-evening target. Joe From jop at astro.columbia.edu Fri Dec 13 12:06:42 2002 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 13 Dec 2002 12:06:42 -0500 (EST) Subject: (cba:news) New stars for the solstice Message-ID: Dear CBAers, Time for a report on campaigns. We have 40 days now on Tau-2, enough to prove the main signals in the star... namely the ones I described in my last message. It's enough to go to press with. It was a tough decomposition, because there are *three* closely spaced frequencies, with 6.488, 6.712, and 6.876 (all +-0.006) c/d, along with the nodal frequency itself at 0.165 c/d. Time to sweep the star off the stage. Thanks to all who contributed, I know this star gave pretty ugly light curves and I appreciate your keeping the faith! A star that gives *beautiful* light curves, but which has only been discovered by a few of you, is EC04224-2014. It's high time to attack this star with vengeance! Well, anyway... with vigor. Well placed for south and north (other than northern Europe), transiting near midnight, and bright as a sonofagun (about 12th). Waves of great pulchritude in the light curve. I guess we should give up on FY Per. It is so devoid of activity that we just can't see anything at our level of accuracy. Once in a while it seems to break into 90 minute oscillations, but those occasions are rare (none this year). I think I'll send the data off to Jeff Robertson, and hope that he can make something of it! We've just started a campaign on V1062 Tau. This is a tough star, at ~15.6, with a 10-hour orbital period, and besieged monthly by the rampaging Moon. But it has a cute 1-hour rotation period, and that means it's one of OURS. A fine target for all northerners... and brave southerners too, I earnestly hope. Also starting up is DW Cnc. This star will knock your socks off. Still a little early in the season for Cancer, but a good target for morning observation. We'll be ramping up the pressure in Jan/Feb. Finally, there's FS Aur. Like FY Per, we've not figured this guy out at all. It has a 3.4 hour photometric period, but the orbital period is 1.4 hours, and we are basically clueless as to the origin of the photometric signal. So, as observers, we need to study it carefully to learn its short- and long-term coherence. A pretty good northern target, even for small scopes since the quantity of interest is that 3.4 hour signal (long period and decent amplitude means signal-to-noise issues are tractable). I just taught my last class yesterday. What a relief to have the pressure off! It was a cosmology class, and I taught it historically, which means that I essentially moved steadily back in time. Going back to about t=1 minute, it still seemed like physics... and then it quickly (of course) turned into theology. Made me really uncomfortable... nice to resume thinking about *stars* again. joe