From jop at astro.columbia.edu Mon Feb 6 14:35:36 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 6 Feb 2006 14:35:36 -0500 (EST) Subject: (cba:news) erupting stars, etc. Message-ID: Dear CBAers, Lotta stars popping off up there. Let's talk about them, and other program stars. The two just-erupted stars are OU Vir and YY Dra (=DO Dra). I suggest skipping OU Vir (since we covered it very well last time around) and making a big effort on YY Dra (since we've never observed an outburst "in season" before. Fire away! FS Aurigae also just erupted, and was caught by Bart Staels. I found the light curve fascinating... but it's somewhat likely to be back to minimum (~16th mag) by now, since the few known eruptions have always been very short. Someday that might change. Anyway, since Auriga is atill reasonably available, this is a good targe - for at least a few days. In my opinion, it's time to quit on ASAS0233-10. The star is getting faint, the moon is getting bright, and we already know both periods (Porb and Psh) pretty well. IGR0023+61 = RX0022+61 remains a VERY VERY GOOD TARGET, For all the reasons described before. A definite special for residents of the frozen north. ASAS1025-15 (Hya) renains available and bright, and might be a good target for a few more days. But I do think that YY Dra is definitely the better choice in the morning sky. Finally, there's still T Pyx. We still don't have enough data to produce a seasonal timing of minimum (accurately, anyway). Let's remedy this! joe From jop at astro.columbia.edu Mon Feb 13 21:02:40 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 13 Feb 2006 21:02:40 -0500 (EST) Subject: (cba:news) Swift J0732.5-1331 Message-ID: Dear CBAers, The full moon has clobbered many of our choicer targets... but here's a new one which promises to be very interesting, can survive a little moonlight, and is decently equatorial. It's a Swift X-ray source - a quite hard X-ray source, which strongly suggests that it's a magnetic CV. For proof, though, that's where you come in! So let's go after this star with all hemispheres and as many telescopes as possible. The ASAS dwarf novae have I think run their course (ASAS0233 and 1025) - time to close 'em up and turn to fresh targets! ~10" away from a much brighter star, so be careful with the data analysis: http://www.astro.columbia.edu/~jules/SwiftJ0732.5-1331/ 07 32 37.6 -13 31 09.0 It's a USNO-B1 star joe From jop at astro.columbia.edu Fri Feb 17 10:51:45 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 17 Feb 2006 10:51:45 -0500 (EST) Subject: (cba:news) Swift J0732.5-1331 In-Reply-To: Message-ID: Hi Bernard and Tom et al., Don't give up on this star! We've got lots more to learn about it. I too was quite surprised when the light curve appeared so flat and boring... but after popping it into a power-spectrum program, I saw that there's actually a couple of stable and fast periodic signals in it: at 167.2 and 337.2 c/d. These are *roughly* commensurate - but within measurement error they're not, so I tentatively interpret them as independent signals. This in itself suggests an intermediate polar classification... but then the light curve is so flat, that's awfully surprising for a CV (much less so for a low-mass X-ray binary). Anyway, please keep the faith - the science reward will certainly be excellent, even though the light curves look... well, embarrassing. joe From jop at astro.columbia.edu Sat Feb 25 07:33:35 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 25 Feb 2006 07:33:35 -0500 (EST) Subject: (cba:news) Swift 0732-13 and IGR 0023+61 Message-ID: Dear CBAers, These two fascinating stars, which our coverage seems to identify as new DQ Her (intermediate polar) stars, are really sailing off into the sunset now. We're urgently trying to accumulate enough late-season light curve to tie down all the periods - before we enter the morbid 5-month silence inflicted by the mischievous Sun! Only a few people can do IGR 0023 now - mostly Schandinavians maybe. Still, if they can tear themselves away from their Olympian successes in Italy, it's likely to be a very good target for a little while longer. Swifty (0732-13) is an utterly fascinating star. We are getting very good coverage from New Zealand (Grant Christie, Jennie McCormick, Robert Rea) and just a little help from other longitudes. There are several very rapid periods present: 512 and 256 s (our little binary pulsar), and possibly a couple of others. Strangely - VERY STRANGELY! - the spectrum is practically a perfect match to a G star. The star is near V=14.0 and hardly budges; it looks like a flatliner, but deep in those tiny wiggles there beats the pulse of a hellacious mystery. The next week is really critical for coverage. After that, an evening Moon will start to interfere... and a bit later, lingering twilight. So... except maybe for extreme borealites, try to get this star before it gets clobbered by Sun and Moon. Coverage in Australia, North America, and the Europe-Africa longitude is especially lacking - and would be great! joe