From jop at astro.columbia.edu Fri Feb 8 17:25:50 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 08 Feb 2013 17:25:50 -0500 Subject: (cba:news) Stars for February In-Reply-To: References: <51152bb0.294e420a.709e.ffffea2eSMTPIN_ADDED_BROKEN@mx.google.com> Message-ID: <51157B6E.4090700@astro.columbia.edu> Hi Joe et al., I've been in South Africa at a nova conference, and it's a little hard to keep track of which stars are quite ripe right now. In the north, that is. In the south, it's a slam dunk: CP Pup and T Pyx (time to renew coverage of the latter now). But two stars which are now desirable to observe at some length are BY Cam and "Paloma" (0524+42). Both are candidate or likely "asynchronous polars", and we'd like at least 1-2 more weeks to conclude coverage. ER UMa is also a good candidate, as Enrique said. V1159 Ori is over. I'm not sure I said that before... but February is too late for Orion. It was an awfully good year! Although we're mostly giving BK Lyn a rest this year (after last year's frency), we do want to peek in on it every so often to see when the supermaxima occur, and if possible measure one of the superhump periods. I notice that AAVSO data doesn't define either. So it appears that if we don't do this, no one will. It would be awfully nice if *someone* will decide to be the BK Lyn specialist. Pretty nice star to specialize in... and it would be unfortunate to lose track of cycle counts (for the supers) after investing all that energy in 2011-12! The various DQs (intermediate polars)continue to be good targets for shorter observations. joe On 2/8/2013 1:57 PM, Enrique de Miguel wrote: > Joe, > > BY Cam is definitely a good target for the first half of the night. > > I would suggest you ER UMa for the second half. The superoutburst ended few days ago and it has just gone through the first normal outburst of the new supercycle. > We don't need a dense campaign on ER UMa, but just few runs to show (as I suspect) that is still showing negative superhumps. They should be definitely more > clearly visible now that is in its low state around 15.0-15.5 mag. > > Enrique > > > > > On Feb 8, 2013, at 7:30 PM, Joe Ulowetz wrote: > >> Mark, >> >> I'm thinking of joining you on BY Cam. With our locations we wouldn't >> overlap much and, when you're running again, be able to cover it for longer >> time series. Unless someone suggests a higher priority target in the next >> few hours, I'll plan to do that tonight. >> >> Thanks, >> -Joe U. >> >> On Fri, Feb 8, 2013 at 10:44 AM, Mark Salisbury < >> mark.a.salisbury at btinternet.com> wrote: >> >>> Hi >>> >>> I've been following BY Cam in the few clear nights we've had but the >>> weather >>> has been atrocious in the UK so it's not been easy. Unfortunately a >>> technical problem will keep me out of action for a couple of weeks now. >>> It's an interesting target to follow so I'll carry on with it soon as I'm >>> up >>> and running again. >>> >>> Rgs >>> Mark From jop at astro.columbia.edu Sat Feb 9 01:35:31 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 09 Feb 2013 01:35:31 -0500 Subject: (cba:news) Fwd: [vsnet-outburst 15091] TCP J15375685-2440136: large-amplitude transient In-Reply-To: References: Message-ID: <5115EE33.4040401@astro.columbia.edu> Wow, this star's a little out of season, but kind of sensational. Dwarf novae in (super)outburst are a pretty good standard candle at absolute magnitude 4.6. That makes this one about 12.7 in quiescence, which is faint even for a bare white dwarf - so the accretion disk must be really, really faint. We love such stars, and there are precious few of 'em. They're probably the oldest CVs in the zoo, and that's where we've had some of our best successes - in geriatric CV-ology. Not convenient for anyone (since southerners have short nights now). But let this star not go unmolested. Fight the good fight against airmass and twilight. joe TCP J15375685-2440136: large-amplitude transient Itagaki-san has informed that he detected a bright transient. 2013 02 08.7797* 15 37 56.85 -24 40 13.6 13.6 U Lib http://www.k-itagaki.jp/images/tcp-lib.jpg GSC 2.3.2 gives j mag of 21.74. The outburst amplitude is 8 mag. The object looks likely a WZ Sge-type dwarf nova. Observations are encouraged. From jop at astro.columbia.edu Sun Feb 17 07:05:15 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 17 Feb 2013 07:05:15 -0500 Subject: (cba:news) midwinter changes; the south shall rise again Message-ID: <5120C77B.7020901@astro.columbia.edu> Dear CBAers, Just back from the nova conference in South Africa. I had hoped to see Berto there, but class commitments back home were too severe. It was a good conference. I was surprised how much disagreement there is among nova theorists. In large measure this has been sown by the continuing provocation of new data - it's tough to survive collision with new facts! Great motivation for us observers. T Pyx is certainly a good example. The large and abrupt period increase in outburst was a shock. We could explain a tiny period increase (mass loss), or a period decrease of almost any size (angular momentum loss). A big period increase requires hefty mass loss, which we don't expect from a recurrent nova (since it has only had a few years to accrete). We'll come up with some sort of excuse, of course... until the next surprise comes along. We have been going great guns on our two big southern targets: T Pyx and CP Pup, with huge efforts from Arto, Berto, and Bob Rea - aided also by Peter Nelson, Gordon Myers, Josch Hambsch, and Shawn Dvorak. Now it's time to halt the campaigns, for two completely different reasons. For T Pyx, the signal appears to be completely stable; a few runs in April will tweak the value of Porb, but it's not a useful target until then (unless the star blows up again!). Time to quite also on CP Pup, for (sort of) the *opposite* reason. This star astounds me. There is a fairly good - not beyond any doubt, but pretty good - spectroscopic measure of Porb at 0.06143 d. And that signal appears to be also weakly present in the photometry. But the stronger photometric signal occurs at lower frequency, and some 1993 data - very sparse by our current standards - convinced me that was a common superhump, about 2% longer than Porb. Now that we have long observing campaigns in three recent years, I see that this is wrong. Actually the signal is 10-100 times less stable than a common superhump, and on average about 5% longer than Porb (and much larger in amplitude than a common superhump). Anyway, the coverage has become nearly perfect, and it's now clear that the signal - large though it is! - is so unstable that long baseline is of little use in improving its study. It's QUASIperiodic, not periodic. Quite fascinating, and susceptible of interpretation, but not needing any more data. Time to end coverage of V1159 Ori, too. The best evening object for all hemispheres right now is definitely GR Ori, a long-dormant eruptive star which now appears to be an extreme dwarf nova (not fully confirmed yet, but very likely). Another in Rod Stubbings's amazing gallery of finds. Some of you are already observing it - nice move - and might want to send some useful info to this space. AAVSO Special Notice 335 contains the information you need to observe it (including the correct coordinates). This is probably a really extreme WZ Sge-type dwarf nova, our favorite beast! It's 23rd magnitude at quiescence, so savor it (and acquire time-series photometry) while ye can. In the morning sky, if you can, I strongly recommend TCP 15375685-2440136, another new kid (dwarf nova) on the block who has erupted off-season. I guess the odd ones can't be expected to cooperate. Coords and finding chart in the last cba-news message. At a similar RA, but at -52 deg and near magnitude 18, is IM Nor, which jumps to my high priority list, now that T Pyx has done its dance. In our group, only Berto has ever observed it. But it would be GREAT to obtain time-series photometry around the globe, sufficient to define the main (orbital) signal and search for others. Same comment for V382 Vel (Nova 1999), although this one is more exploratory; how about one lengthy time series to determine magnitude and assess likelihood of periodic signals (present when we observed it 7 years ago). A bonanza of southern stuff! I'll write again in the next 1-2 days re our decidedly-northern targets, which I think are still good. But Enrique keeps better track of these, and may write in the meantime. joe From jop at astro.columbia.edu Tue Feb 19 22:21:01 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 19 Feb 2013 22:21:01 -0500 Subject: (cba:news) T Pyx paper Message-ID: <5124411D.4080402@astro.columbia.edu> Hi CBAers, Our massive T Pyx paper, representing ~4000 hours of data during 1998-2013, is nearing completion. Whew. Or more correctly, the short version of it is, which I'll send you in 1-2 weeks after you send a little more information. I have the following co-authors listed: Arto, Berto, Bob Rea, Josch Hambsch, Jennie, Peter Nelson, Jonathan, Bill Allen, Tom Krajci, Simon Lowther, Shawn Dvorak, Tom Richards, Gordon Myers, and Greg Bolt. For the longer version, which will follow 1-2 months later, I'll need current emails and addresses for each of you. About half of you already did this for papers on other stars, in the last few months - either to Jonathan or to Eve Armstrong. But if you didn't, then send 'em to me now. I'm not sure I strictly need 'em for the short version now, but I definitely will for the long version. I've really enjoyed writing up the T Pyx data. Such a fascinating and unique star, and possibly holding the key to how CVs end their lives (as recurrent novae gone wild, but *not* becoming supernovae). Arto and Berto, you've been carpet-bombing this star with time-series photometry. Do you hate it now... or love it... or are you emotionally detached from exactly whose photons are being captured by your silicon? BTW, it's useful for archiving, referencing etc. to go by one consistent name in the literature. For example, I've tried to use "Joseph Patterson" - but occasionally something slips in with J. or J.O. or some such thing. Sometimes I can't find my own paper... and we all know the libraries are getting dismantled. So it would be useful to specify exactly the professional (astronomical) name you prefer. joe From jop at astro.columbia.edu Thu Feb 21 08:18:57 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 21 Feb 2013 08:18:57 -0500 Subject: (cba:news) Fwd: Re: Next HST observations: HM Leo In-Reply-To: References: Message-ID: <51261EC1.3000607@astro.columbia.edu> I'm sure you guys all know the drill by now... but don't assume that someone else will do it, or that "it's too late". Each of these HST observations is only permitted by NASA if it's demonstrated that the star is in quiescence. Send the magnitude right away to Boris. And for the observation itself, in case it happens, it's very useful to know the simultaneous visual magnitude. That solitary point can often have great weight in fitting the flux distribution (since the spectra themselves are in the UV). joe -------- Original Message -------- Return-Path: Received: from sedna ([unix socket]) by sedna (Cyrus v2.1.18-IPv6-Debian-2.1.18-1.cal.sarge2) Dear All, in case that any of getting another image of HM Leo *right now* - please let me know as soon as you can. Thanks so much! Boris ----------------------------------------------------------------------------------------------------- For more information on this HST program, see http://deneb.astro.warwick.ac.uk/phsdaj/public_html/12870/ http://deneb.astro.warwick.ac.uk/phsdaj/public_html/12870/Targets.html From jop at astro.columbia.edu Fri Feb 22 09:59:22 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 22 Feb 2013 09:59:22 -0500 Subject: (cba:news) GR Ori struts its stuff... Message-ID: <512787CA.2080700@astro.columbia.edu> as shown by Berto Monard's and Bill Stein's observations this past night. Big superhumps - the real ones, not the little double-humped ones we've been staring at - and this star is certainly now a great evening target for telescopes of all persuasions. Super. We're going to need a lot of longitudes to keep good track of this equatorial star! joe From jop at astro.columbia.edu Tue Feb 26 11:27:48 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 26 Feb 2013 11:27:48 -0500 Subject: (cba:news) TCP1537-24 again Message-ID: <512CE284.8000505@astro.columbia.edu> ... and I see that Tom's data the last two nights appear to establish that the bona fide superhumps have begun. Still some problems with alias breaking - but this newly-discovered dwarf nova is likely to be a great, great target for weeks to come! joe From jop at astro.columbia.edu Thu Feb 28 04:30:19 2013 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 28 Feb 2013 04:30:19 -0500 Subject: (cba:news) t pyx and TCP1537-24, mainly Message-ID: <512F23AB.70302@astro.columbia.edu> Dear CBAers, Thanks to Jonathan, attached is the short-version of our T Pyx paper. It should also appear on astro-ph in a few days... and a longer version - with much more data, data analysis, and speculation - 1-2 months later. We're through with T Pyx for the season - or at least for March. Some observations in April will keep the ephemeris tight, and establish the new period with sufficient precision to bridge to future years. Bill Stein is continuing to study TCP1537-24, but otherwise this (likely very) important star is getting neglected. It would be great to cover this dwarf-nova during its first-ever outburst! Two other stars. Nova Mon 2012. We still seek long light curves of this star. Decently placed for all hemispheres. The period is long - 7 hours - so you need long runs (>4 hr for sure), but it's important to define the light curve in this, year zero after eruption. YY Sex. This has been off our lists for a few years. There's a stable ~100 minute period, and the stability of that period is enough to convince me that it's an AM Her star (only an orbital period could be *that* stable). But the quality of our limit would now be 2-3 times better, since more time has elapsed. It's a nice target for a bright Moon, since the orbital modulation is huge in I light. Enrique, can you update on the other long-term dwarf-nova studies? Especially ER UMa and OT0754+38. And re BK Lyn, I'm inclined to think that somewhat more coverage is desirable, to keep track of the period. Do you agree? joe -------------- next part -------------- A non-text attachment was scrubbed... Name: tpyxasp.pdf Type: application/pdf Size: 173039 bytes Desc: not available URL: