From jop at astro.columbia.edu Tue Apr 8 16:50:21 2003 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 8 Apr 2003 16:50:21 -0400 (EDT) Subject: (cba:news) springtime stars Message-ID: Dear CBAers, Time for some changes up there. Northerners have leapt into the breach on UMa6, and southerners on WX Cen. We have very high-quality mean light curves for these eclipsing stars, and we can basically quit for the year. I'm still anxious to pick up EC10578-2935 before it recedes too far to the west. However, the signal is subtle and the star not so bright for the bright-moon conditions coming on. If you can get long runs of quality on it, that's a very good target. There are three other southern targets to mention: BR Lup - presently bright (superoutburst) and showing nice humps. Great target for the next 10 days or so. EX Hya. A venerable star, but oddly never the target of a CBA campaign. It is time to remedy that oversight! Well positioned for all southerners, and some folks in the southern USA as well. Finally, IM Nor. Woudt and Warner just published a little paper announcing the orbital period - 2.5 hours, just the second short-period guy found among the recurrent novae. The mean mag is 16.5 and the modulation is only 0.10 mag or so... but I know from experience that this is the kind of wave we can easily track, since it is almost exactly like T Pyx in all these respects (just 1 mag fainter). Let's tighten up that orbital period! In the north, away with UMa6, and also DW Cnc and PQ Gem - their seasons are basically over. BG CMi is still timely, and CR Boo and EX Hya. The main northern stars I wanted to hype are HZ Her and V533 Her. The latter is showing a very stable QPO - disturbingly stable for a process generally regarded as incoherent. This needs much better documentation. And just as we have criminally neglected EX Hya over the years, HZ Her is another star that should have been on our lists for many years. So let's launch that campaign pronto. I'll write later in the week re comp stars and such (but some of you might want to write to "news" and recommend some) Lotta teaching this week - back to the trenches! joe From jop at astro.columbia.edu Sun Apr 27 14:16:43 2003 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 27 Apr 2003 14:16:43 -0400 (EDT) Subject: (cba:news) southern cbaers, and some from Hyperborea too Message-ID: Rod Stubbings reports an outburst of V551 Sgr, a dwarf nova that rarely erupts and is a good candidate for "WZ Sge" status. So this could be a great opportunity - if it turns out to be a super. The star is at 1800-34 - so it is *marginally* suitable for some northern coverage. Obviously mainly for the australites. The field is crowded, of course. 2000 coords 18 00 56.5 -34 35 45... methinks you'll need a chart better than the Downes & Shara chart. Jonathan, could you toss a good one up on the website? EC10578-2935 is finished. We have a very fine period of 3.23 hours - an immensely popular period for novalike variables. Kudos to Robert Rea and Berto Monard for wrapping this one up securely. Lots of good EX Hya data rolling in, and may it keep rolling. In the far north, I've just learned about 1RXSJ062518.2+733433 (whew), a 14th mag star that definitely appears to be a member of the DQ Her class. This star is a little off-season, but it would be great to accumulate some coverage in the spring before doing an all-out campaign next winter. So if you can work that far north, let 'er rip. The published light curve looks sort of like BG CMi, definitely well-suited for our coverage. This is indexed as "Cam" in the CV catalogue. Full CBA note coming tomorrow. joe From jop at astro.columbia.edu Mon Apr 28 19:46:06 2003 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 28 Apr 2003 19:46:06 -0400 (EDT) Subject: (cba:news) Stars for April/May Message-ID: Dear CBAers, Well, Rod reports that V551 Sgr faded fast. Probably a normal outburst... there's some chance it'll trigger a super, but usually not. Off the menu. The two really good southern targets now are EX Hya and the newly discovered DQ Her star 1RXSJ154814.5-452845 (periods probably 11 min and either 9.4 or 6.7 hours). We should be able to define these periods very precisely and get long-term ephemerides for such a friendly star (14.5) located at -45. The only catch is a 13th mag star just east of the variable. If you search the CV catalogue for "Lup", you'll see the situation. Doesn't look too difficult, maybe 9 arcsec or so... you should be able to manage, but just need to be aware in case of very bad seeing or jumpy drives. Looks like a winner! In the NORTH... If you can reach RX0625+73, it's definitely worth covering for a few weeks. Then we pick up again after it comes out of the Sun (ha!). Could get a year of coverage with no systematic substantial breaks... now there's a way to beat aliases! In the morning sky, it's worth starting a new campaign now on MV Lyr. This star waffles around between 12.5 and 18... bounces around so much and so fast that it's been awfully tricky to analyze time series. We found it around 12.7 ten years ago, and obtained a brief campaign showing marginal evidence for superhumps. Borisov (92) did the same - also marginal evidence, but at least near the same period. Who knows? Anyway, we can do a MUCH better campaign now. It's a little early for these coords (1907+44), but I'm afraid the star might not stay near 12th mag very long. So let's do it. Earlier in the night, we need to keep going on HZ Her for at least 20 more days, to cover the full 35-day precession cycle. Great data coming in on that, from Dave Messier, Jerry Foote, Tom Krajci, Tonny Vanmunster, Bob Fried. And before that, try GZ Cnc again. It just jumped back into eruption, and might finally show the waves that have eluded us in quiescence. About 13.5 I think. Time to retire CR Boo. And give a rest to V533 Her; it'll still be there in 1-2 months, whereas MV Lyr could be a fleeting proposition. Finally, IM Nor, the eclipsing recurrent nova. This is a difficult star but is I think the most important of the southern targets. With small apertures (like most CBA), it needs quite good conditions - little moon and good seeing. Berto got one good run - let's see if we can get another half-dozen and patch together a good eclipse timing (by the way, it's a *shallow* eclipse - "dip" might be a better word). joe