From jop at astro.columbia.edu Fri Oct 5 14:43:17 2007 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 05 Oct 2007 14:43:17 -0400 Subject: (cba:news) V455 And and RX0232-37 Message-ID: <470685C5.7090607@astro.columbia.edu> Dear CBAers, Well, the V455 And = HS2331 coverage continues good, though down from the frenetic pace of mid-September. The main periodic signals are basically standard fare for some of the WZ Sge stars: a strong signal at Porb - with an origin still unknown - followed by a superhump. No certifiable echo outbursts yet, but they could still come. An important and unexpected wrinkle is the fast signal at 68 s. It's actually present throughout the outburst, and CBA data will specify what happens to the phase/period as the outburst fades. Keep that fast photometry coming (and by the way, if you possibly can, specify time to 6 decimal places (JD xxx.yyyyyy). Probably that sixth place is unimportant... but in playing with the data, I've noticed that roundoff errors can be detectable. For most of you, though, I imagine that the star's faintness, your readout time, and timekeeping accuracy will keep you away from studying this signal. That's fine - the most important lessons we're likely to learn from the eruption reside in the behavior of the slower periodic signals, and the eclipses. Cycle times around 40-60 s are likely to be just fine. I've been delinquent in not writing about RX0232-37. This is a newly erupted dwarf nova, and Greg Bolt has found strong superhumps... so it's one of our friends. I believe it's still around V=11.7 or so, and may become quite an important star since it has to be quite nearby. This is really well placed for southern observers, and I fervently hope you'll spring to action pronto! (Even though I didn't.) The J2000 coords are 02h 32m 38.13s -37d 17m 54.7s Find yourself a nice comp star and fire away! Having reached 10th mag or so, this star has great, great potential. joe From jop at astro.columbia.edu Wed Oct 24 10:06:05 2007 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 24 Oct 2007 10:06:05 -0400 Subject: (cba:news) october-november stars Message-ID: Dear CBAers, Well, the flow of data from the V455 And has been immense, and of a quality which should be sufficient to define the properties of the outburst quite well. I've been kept busy tracking everything day by day; our data illustrate the various changes in eclipse shape and in 68 s pulse phase (which stays pretty constant, although has to be studied mainly by using the 34 s first harmonic). To a first approxi- mation, it seems that the pulse phase charges right on through the outburst, as if nothing is happening! This is more or less what you expect if the signal represents the spin period of a rapidly rotating white dwarf. Soooo..... I guess it does! That's good enough for me. I think it's still very desirable to obtain long nightly coverage of V455 And - for another month or so. But the frantic search for better time resolution - well, we can call that part off. Cycle times of 30-40 s probably suffice to define the other fine detail of the light curve: the variable eclipse shape. This is of very great interest; if you've been covering it, keep it up! BTW are there new V455 And time series (from the last 10-15 days) in the pipeline? I suspect there's some European data on a slow boat.... I'm hardly ever concerned about this, but I wanted to fast-track all this data, and it would help a lot to prepare FINAL nightly light curves... The other prime northern target is RX0022+61 = IGR0023+61 = "Cas". We got a boatload of coverage last year, but not quite enough to solve all the aliasing (and borderline signal) issues. This is an excellent target for all-night photometry over the next six weeks. BTW this is NOT the same star as V410 Cas, which lurks dangerously nearby. Later on in the northern nights, new and hardly-studied DQ Hers come into view. I highly recommend RX0636+35 = "Aur" and RX0704+26 = "Gem". Plus V405 Aur, an old friend we haven't visited in years. Peachy targets for those brisk, clear mornings of October and November. The Milky Way's in the far north now, so the pickings aren't quite as abundant in the south. Here's the big three that I see. (1) BW Scl. The southern V455 And. Just as rich in periodic signals, no eruptions yet known. About 16.5, so perhaps will need a fully clear night. (2) RX0232-37 = For (but I believe not in Downes et al.). Seemingly another WZ Sge star... but the light curve has new surprises (it's rising again), and the superhump endureth. Might not erupt again in your life. (3) SDSS0407-06 = Eri. A great, great negative superhumper, or at least it was 2 years ago. I'd like to run a big campaign in December from both hemispheres. But early-season data now would be mighty nice. Happy observing! I hope to see a few of you next week in Cambridge (AAVSO meeting). joe