From jop at astro.columbia.edu Wed Nov 6 08:13:30 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 06 Nov 2013 08:13:30 -0500 Subject: (cba:news) QR And, V378 Peg, VZ Scl Message-ID: <527A407A.6000006@astro.columbia.edu> Hi CBAers, A few stars to update their status on our menu. QR Andromedae. Job done. We have enough eclipse timings to measure the rate of orbital-period change, which is very fast (timescale of 2x10**6 years). Just like T Pyx and V Sge, and possibly a *universal* signature of supersoft binaries. We'll be trying this with a few others over the next year, and test the hypothesis. V378 Peg. I think we have enough. The star still exhibits the same (exact) period seen by Ringwald and Kozhevnikov. Unfortunately we don't have really decisive evidence of what Porb is... and almost certainly that will require spectroscopy. (Ringwald published a spectroscopic P, but the baseline was only 1 day, just not enough to clarify the matter. We don't need more photometry now. The path forward now is probably to guilt some spectroscopist to invest a few nights in studying the radial velocities. VZ Scl. Wow. Josch Hambsch and Bob Rea invested some serious time in this one, and the 3-week record revealed an obvious 3.3 hour negative superhump. Wow - another high-Mdot "SW Sexer" coughs up its photometric secrets (which it has been hiding for 40 years). It's now desirable to make an intense effort for ~2 more weeks, to sharpen up the period, look for harmonics, and the very-low-frequency (~4 d) signal usually accompanying negative superhumps. It would be really good to get coverage from some of the missing longitudes: Australia, Africa, and (southern) Europe. With the deep eclipses exhibited by VZ Scl, it might also be possible to trace the changing *shape* of the disk as a function of "precession phase". We've never quite succeeded in this, but it seems like it should be possible, for sufficiently big superhumps. I hope to give similar status reports on other targets in a few days. Berto has been observing ES Cet and a new dwarf nova, CSS J024354.0-160314. The first is worth observing throughout the observing season; the second, for at least a week. For those of you who don't know the CRTS website, you'll be delighted to discover it. Among other goodies, it supplies a finder chart and historical light curve. Beautifully designed, and the source of all the CSS stars that are starting to become an important part of the CV world. Can someone clarify MASTER OT2348+25, the candidate helium star? How bright is it now? If it's still doable, it's definitely the priority target in the evening sky. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri Nov 15 15:19:02 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 15 Nov 2013 15:19:02 -0500 Subject: (cba:news) OT0057+44 Message-ID: <528681B6.6020004@astro.columbia.edu> Dear CBAers, MASTER OT J005740.99+443101.5 is a great dwarf nova - eclipsing, superhumping, and freshly discovered. Most of you already know about it, but I just wanted to loudly beat the drums for it. Around mag 16.6 now... but probably will fade only slowly in the coming days, so we'd love to get another week or so of time-series photometry on it. With the eclipses and superhumps, you don't need great S/N to contribute usefully on it! Also: let's *end* the campaigns on V513 Cas and IW And. More details in tomorrow's message. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Mon Nov 25 22:47:17 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 25 Nov 2013 22:47:17 -0500 Subject: (cba:news) stars for November-December Message-ID: <529419C5.3060509@astro.columbia.edu> A non-text attachment was scrubbed... Name: cba1125.pdf Type: application/pdf Size: 34320 bytes Desc: not available URL: -------------- next part -------------- Dear CBAers, First school vacation all fall. Time for revising the menu. V513 Cas and IW And. Time to stop. I think everybody has... but just in case. OT0057+44. Still a good target if you can reach it (17-18 now) with decent S/N. VZ Scl. We have about a 45-day baseline now. The star has eclipses (of course), a powerful negative superhump, and something else I can't quite decipher. It could be a positive superhump, which beats with the negative guy and thereby changes the hump amplitude... or it could be just an intrinsic amplitude modulation in the negative guy. Or something else altogether. But I think it's just too late in the season to tell for sure. So let's close it down for the year, and resume next August! Josch and Bob Rea have really done yeoman service on this star, with some critical runs also by Gordon Myers. AQ Men. Great southern target. Our recent MNRAS paper (Armstrong et al.) demonstrates something quite unusual in this star. In addition to negative superhumps (which I suppose should no longer be considered "unusual"), the star seems to have *variable* eclipses - occurring on a precise period, but with a profile that varies a lot. Is this variation cyclic, and if so, is the cycle time equal to the beat period between orbit and superhump? Let's find out! AH Men. I wrote a paper on this far-south star back in 1995, based only on data from Chile. But there were zero southern CBAers then, and we can do so much better now. It's a bright star and a respectable SW Sexer, with a light curve complicated by the simultaneous presence of negative and positive superhumps (I think), and by the presence of an annoying intruder star about 4 arc-sec away. If you can get photometry by excluding that star, then fine. But most of you would likely prefer including it, and then subtracting its light (assumed constant). If the latter, then you might want to observe in BLUE light, where the CV is substantially brighter than the intruder. AH Men is bright enough (~13) to survive the filtration. Settle on one of these strategies, then stick with it; that's the usual CBA prescription. V902 Mon. Shiny new intermediate polar, eclipsing, equatorial. Just an all-around great star - let's try to follow it around the globe! BY Cam. Now's the time to resume lengthy runs on this well-placed star. It's up to us to measure this star's slow rate of spin-up. Someone's gotta do it! Easy northern target. A couple miscellaneous hunches: LS Cam and BZ Cam. Tantalizing...we've never quite figured out what these stars are. BZ Cam is very bright and would be a good small-scope target for long runs. A few well-placed DQ Her stars: V647 Aur, V418 Gem, HT Cam, BG CMi, MU Cam, V667 Pup. Short (2-hour) runs usually OK, but long is always better. Then there's IGR 0457+4527 (Masetti et al. 2010: 04 57 6.98 +45 27 48.5), a 17th mag DQ Her guy which has not yet been properly published. *Great* target if you can go that faint. joe p P.S. I hope people are thinking at least a little bit about the upcoming SAS/AAVSO/CBA meeting at Ontario (CA) in June. -------------- next part -------------- ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/