From jop at astro.columbia.edu Tue Aug 7 09:31:15 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 07 Aug 2012 09:31:15 -0400 Subject: (cba:news) V380 Oph Message-ID: <502118A3.7070505@astro.columbia.edu> Dear CBAers, We're hoping to get an HST observation of V380 Oph, which has entered a low state, quite soon. To do that we have to monitor it visually with sufficient depth to get an idea of how bright it is. The fainter, the better... partly because it certifies that the white dwarf is dominating the light (the aim of the observation), and partly because a BRIGHT V380 Oph will fry the detectors (and therefore be forbidden by NASA). Snapshot magnitudes of V380 Oph are the main thing that's needed, rather than time series, which of course are our usual specialty. And - again unusual for us - "it's too faint for me" is not really an appropriate reaction here. Add frames, lengthen exposures, do whatever you need to measure the magnitude. It's likely to be around magnitude 18-19, maybe fainter. The HST observation probably won't happen till mid-September, but to proceed with the planning, we need some knowledge of its variability pattern. Some of these deep-low-state stars have brief flares by a couple of magnitudes, while others just sit there inert, faint, and unvarying. Over the next few weeks, we need to learn more about V380 Oph in that regard! We'll also be trying this with big scopes, where S/N isn't a problem... but a few snapshots don't really answer the question. We need to know the pattern of variability, and that's where CBAers can provide the answer. joe From jop at astro.columbia.edu Wed Aug 15 19:21:37 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 15 Aug 2012 19:21:37 -0400 Subject: (cba:news) V380 Oph, no dice Message-ID: <502C2F01.8080500@astro.columbia.edu> Hi CBAers, We're satisfied now that V380 Oph is only in a semi-low state, not a really deep low state, which would have warranted an HST observation. So: job well done. However, before concluding it, could someone get a long time series? The snapshot data suggested there may be a periodic signal there - could someone check? Also, take RX2133+51 off the list. We've got enough now to bridge the data gap back to 2011, and can retire the star for the year (or possibly until December). It's a good season for GD 552 - keep up the steady coverage on that star! joe From jop at astro.columbia.edu Thu Aug 16 09:24:57 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 16 Aug 2012 09:24:57 -0400 Subject: (cba:news) Fwd: centennial of the expanding universe In-Reply-To: <502CB059.4040702@astro.columbia.edu> References: <502CB059.4040702@astro.columbia.edu> Message-ID: <502CF4A9.4030902@astro.columbia.edu> Dear CBAers, I apologize for being neglectful of CBA biz over the summer. Fortunately, Enrique has taken up much of the slack... and as usual, you guys do a good job mentoring each other. Among other things, I've been busy organizing a 100th birthday party for the expanding Universe. This is WAY far from our mission as guardians of variable stars... but as the registration list gets more varied and interesting with each passing week, I think the subject might well interest some of you too. About half the people won't be presenting, and about 1/3 are some variant on "amateur astronomer" (artist, writer, politician, observer, AZ resident, etc.). Here's what I just sent my colleagues at Columbia, along with the conference flyer and the present list of abstracts for talks. If you're interested, you can register (details at the Lowell Observatory website). You don't need permission; if you read these messages, then you traffic heavily in the arcana of stars... and that puts you way over the threshold for seriousness! (A few conferees might not be, but they couldn't possibly be CBAers.) It costs $190, but includes breakfast and lunch on both conference days (Fri and Sat), plus the Thursday night reception at Lowell. Hotel's decently cheap too ($109/night). I see from Donn Starkey's data that V380 Oph has jumped up to ~15.6. That's the last straw - it's off the list! But two months have elapsed since we quit on V1974 Cyg - let's vault that one back into coverage, so we can test for the signal's stability over the full summer observing season. joe Some of you know about the 100th birthday celebration for the expanding Universe that will happen at Lowell Observatory next month. But most of you probably don't... so here's your notice. I attach the conference poster and a list of abstracts to date. It's a conference of astronomers, historians, writers, artists, Slipher's family... and even a politician (just in case you thought you could briefly escape that blight). A small (50-60) and eclectic conference in an observatory/museum/park setting. What exactly happened 100 years ago, and in the 20 years following ("The Day The Universe Changed")? Where have we come since Lemaitre's expanding balloon? Still some more writers/historians (Marcia Bartusiak, Dava Sobel) are likely. Astronomers too, for that matter. Three Columbians so far (me, Helena, Emir - an undergraduate). You'll find more information on the Lowell Observatory website. Registration open till August 30 - lemme know if you have further questions. joe -------------- next part -------------- A non-text attachment was scrubbed... Name: confin2.pdf Type: application/pdf Size: 302333 bytes Desc: not available URL: -------------- next part -------------- A non-text attachment was scrubbed... Name: aztalks.pdf Type: application/pdf Size: 107747 bytes Desc: not available URL: From jop at astro.columbia.edu Sat Aug 18 06:56:40 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 18 Aug 2012 06:56:40 -0400 Subject: (cba:news) Fwd: [vsnet-alert 14858] OT J203937.7-042908: SU UMa-type dwarf nova in the period gap In-Reply-To: References: Message-ID: <502F74E8.1090309@astro.columbia.edu> Hi CBAers, This one definitely looks worth following! Full info on it is contained on the Catalina Sky Survey CV page: nessi.cacr.caltech.edu/catalina/BrightCV.html Superhump observations at this long a period are somewhat rare (because the stars are, not because they don't superhump) - so that gives it a higher importance. joe OT J203937.7-042908: SU UMa-type dwarf nova in the period gap Colin Littlefield has observed this object for two nights and detected superhumps with a period of 2.512(7) hours. The amplitudes of superhumps were large (~0.3 mag). Continued observations are encouraged!