From jop at astro.columbia.edu Tue Feb 1 22:17:36 2011 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 01 Feb 2011 22:17:36 -0500 Subject: (cba:news) Stars for February Message-ID: <4D48CCD0.30101@astro.columbia.edu> Dear CBAers, Sorry for my prolonged silence. Suddenly, actual students have arrived back at school! And I'm grateful for all the leadership you guys have shown with respect to the various stars popping off up there. The dwarf novae have been really putting on a show... and led by Enrique and Tom, the coverage has been just outstanding. I'm still sorting 'em out, but it does look like V1212 Tau and CSS0431-03 will be having a significant impact on dwarf-nova studies - a tad out of the ordinary. And ER UMa is even more interesting, oddly flashing very strong negative superhumps at us. That one shocked me. I've always wanted to do a long study of ER UMa, since it offers the opportunity to follow the variations throughout an entire outburst cycle. But never got around to it. Now, the star cries out for attention... and it's definitely UMa season! So fire away on ER. Unfortunately, I have another UMa star, and another almost-UMa star, to promote. The first is UMa 6 (Downes designation, also known as 4U0928+50). This is a 10.04 hour eclipsing binary, with still no proper publication on it. We need to get about another 5-8 nights on it to complete our study. Not a really big project, but the runs need to be long since Porb is. The second is BH Lyn - another eclipsing CV which we studied in the mid-90s and never got back to. It has pretty good superhumps, but the coverage back in 1996-7 was sufficiently sparse that I couldn't actually distinguish - due to aliasing - positive from negative (i.e. suoerhumps). It should be a snap with long time series from Europe and North America spliced. The DQ Her stars - and I'm embarrassed to be so fond of them when the dwarf novae are flashing such beautiful fireworks - can take a break for a couple months. Though a coupla runs on HT Cam would be nice. In the south, we need to pick up XMM 1151-6237 again, now that it has decently come out of the Sun. Enough to get the first 2011 timings and spruce up the ephemeris. And another 5-6 runs on T Pyx (thanks, Bob!). But the main southern target I want to promote is CP Puppis. This is another star I've been wanting to get back to for 15 years; something always comes up! But let's do it in 2011 once and for all. And by the way, observers in the southern USA can usefully contribute to this one too - I'm hoping for NZ-AU-South Africa-USA. Finally, an update on AAVSO/AAS. I heard from some of you expressing your intention to attend, and others planning on Big Bear instead (granted: cheaper, better weather, beautiful surroundings, closer to our largest contingent, and an always-great meeting). So our little band will be divided, and any "CBA meeting" will wait another year. But I'm still promoting the AAVSO/AAS meeting! If you're planning to attend, remember to join the AAVSO first, since that'll get you into the AAVSO meeting and a serious discount on the AAS registration (which is hefty). I'll soon send out some suggested hotel information in Boston. See the AAVSO website for this May 21-26 joint meeting. joe From jop at astro.columbia.edu Mon Feb 7 09:50:36 2011 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 07 Feb 2011 09:50:36 -0500 Subject: (cba:news) ER UMa shows the way... Message-ID: <4D5006BC.4080703@astro.columbia.edu> But what way that is, quien sabe? A sudden spell of great Mediterranean weather has struck, and Enrique's data shows that ER UMa, in its present quiescence, is flashing very strong negative superhumps. This discovery cries out for follow-up, and in particular much closer study of the ER UMa class. The only real precedent is V503 Cyg, which could be considered a borderline ER UMa star, and which showed a very strong negative superhump persisting for months (Harvey et al. 1995 or thereabouts). But there are other clues hanging around which suggest this could be a property of the class - or, more specifically, could be a signature of an underlying correlate: high accretion rate at quiescence. That would embrace such stars as V592 Cas, BK Lyn, and V1974 Cyg into the club - all with short Porb, all mysteriously bright at "quiescence", and all with negative superhumps. Adding a second mystery doesn't explain the first... but it does suggest an organizing principle for a research program. So: 1. Let's keep following ER UMa until it scrapes the trees on your northwest horizon. Keep cba-chat humming to keep track of who plans to do what, but don't shy away from some redundancy (which really helps with calibration). 2. Let's put YZ Cnc on the program. A bright borderline ER UMa star which CBA has never done. Especially in quiescence, but maybe all the time. 3. Let's put BK Lyn on the program. We have some great data in the bank - but the superhump is so strong and apparently permanent that *this* is the star to test for really long-term stability (months to years). 4. Let's put AH Men back on the program. Same comments as BK Lyn. Still decently seasonal due to the outrageous declination (-81 deg). Other matters. That same spell of great Mediterranean (or European anyway) weather gave us great runs on V1212 Tauri from Enrique and Etienne Morelle, and this puts the star to bed for the year - and maybe forever. Very nice positive (apsidal) superhump. Bob Rea's amazing sentry work has also rung down the curtain on T Pyx. The season had just started, but the photometric wave agrees *exactly* with the long-term ephemeris - so that one's a proverbial wrap. Finally, Enrique has obtain a few eclipses of UMa 6, which tweaks the ephemeris and ends the season for that star also. Fot those wishing to read about the theory of negative superhumps, look up Matt Wood's papers on ADS. They're nicely written and let the reader into the subject with great mathematical gentleness. Michele Montgomery has also written some excellent papers, but she doesn't show much mathematical mercy. The proper word might be STORY, though, rather than theory; the observational basis for the whole subject is still pretty slim! Finally, it would be good to get some late-season data on V1062 Tau. Runs early and late in the season are the key to defining the period sufficiently accurately to bridge the yearly gaps. Any old joe astronomer can observe stars transiting at local midnight - time-series 2-3 months out of season really do the heavy lifting for our ephemeris studies! joe From jop at astro.columbia.edu Mon Feb 7 11:10:44 2011 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 07 Feb 2011 11:10:44 -0500 Subject: (cba:news) Fwd: Re: ER UMa shows the way... Message-ID: <4D501984.60604@astro.columbia.edu> Hi CBAers, Just got this from Arek Olech. So make sure to send your time-series data to him (olech at camk.edu.pl)! joe -------- Original Message -------- Return-Path: On Mon, Feb 07, 2011 at 09:50:36AM -0500, Joe Patterson wrote: > 2. Let's put YZ Cnc on the program. A bright borderline ER UMa star > which CBA has never done. Especially in quiescence, but maybe all the time. Hi Joe, We are covering YZ Cnc using telesopes in Poland and Turkey with significant help of Enrique and Bob Koff. It was in superoutburst in the midle of December. The next superoutburst is scheduled for end of March 2011 with good Moon contitions. Arek From jop at astro.columbia.edu Mon Feb 7 18:06:46 2011 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 07 Feb 2011 18:06:46 -0500 Subject: (cba:news) holy mackerel! Message-ID: <4D507B06.1030001@astro.columbia.edu> According to Jeremy Shears - pretty good authority! - SDSS 1339+48 is at magnitude 10.4. Stop reading this message and fire up a time series. This star is called "UMa" in the Downes catalogue, and is located at 13h 39m 41.12s +48d 47m 27.5s. We have tons of great data on the star in quiescence - and have just been waiting for an outburst. I figured about a 30 year wait, and it's only been 4. As the Green Bay Packers discovered last night, sometimes you get lucky. Within about 2 days we should know if it's a super, though at 10.4 it's likely. A superb post-midnight northern object... good for chat re coverage, though some redundancy of coverage is quite desirable in the very early stages (partly for calibration, and partly to provide some insurance against clouds, equipment failures, etc.). This star trumps the targets I wrote about earlier today. Wow. If you have a V filter, I recommend using it while the star is bright (assuming a suitably bright comp star is around). If you don't (and also even if you do), be careful about saturation. If you are close to saturation, try shorter exposures or de-focus. If you find a particularly good comp star, tell all of us. Likely the best outburst since GW Lib in 2007 - or even better, since it's the first ever seen for Mister UMa. And speaking of GW Lib, we'll be submitting that paper (reporting 1258 hours of 2007-2008-2010 photometry) tonight or tomorrow. Finally. We'll send it to all 14 co-authors tomorrow; if you don't get it and your spam is not too aggressive, it probably means I don't have your correct email address. Leapin' lizards! joe From jop at astro.columbia.edu Wed Feb 16 05:18:16 2011 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 16 Feb 2011 05:18:16 -0500 Subject: (cba:news) Fwd: [baavss-alert] OT J022732.9+130617 : eclipsing polar Message-ID: <4D5BA468.9070503@astro.columbia.edu> This star is way out of season, but eclipsing polars are extremely rare and valuable - so let's give Arto some fine data! joe -------- Original Message -------- Subject: [baavss-alert] OT J022732.9+130617 : eclipsing polar Date: Wed, 16 Feb 2011 11:13:06 +0200 From: Arto Oksanen Reply-To: baavss-alert at yahoogroups.com To: BAAVSS alert Hello from freezing cold Finland! I am looking for another observer for this interesting though quite challenging target. I have observed three eclipses on three nights and it looks like the orbital period is 3.8 hours. As the star is rather low on the evening sky it is difficult to cover two eclipses on single site, so another observer few hours West from Finland would be very helpful. If my prediction holds there should be an eclipse tonight at 20:15 UTC. The star is around mag 16 outside the eclipse and invisible when eclipsed. The eclipse duration is roughly 15 minutes. best regards, arto -- Arto Oksanen arto.oksanen at jklsirius.fi Muurame, Finland ---------- Forwarded message ---------- From: Ohshima > Date: 2011/2/14 Subject: [vsnet-alert 12855] OT J022732.9+130617 : eclipsing polar To: variable_star_forum at yahoogroups.com , vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp , vsnet-alert at yahoogroups.com , vsnet-campaign-polar at ooruri.kusastro.kyoto-u.ac.jp , vsnet-newvar at ooruri.kusastro.kyoto-u.ac.jp , vsnet-newvar at yahoogroups.com OT J022732.9+130617 : eclipsing polar We have received this new object observations from Arto Oksanen. According to this data, ~ 2 mag eclipse is apparently seen though the exact period cannot be obtained yet. __._,_.___ Reply to sender | Reply to group | Reply via web post | Start a New Topic Messages in this topic (1) Recent Activity: * New Members 2 Visit Your Group -------------------------------------------- Visit the BAA Variable Star Section web site at... http://www.britastro.org/vss/ -------------------------------------------- MARKETPLACE Get great advice about dogs and cats. Visit the Dog & Cat Answers Center. ------------------------------------------------------------------------ Stay on top of your group activity without leaving the page you're on - Get the Yahoo! Toolbar now. Yahoo! Groups Switch to: Text-Only , Daily Digest ? Unsubscribe ? Terms of Use . __,_._,___ From jop at astro.columbia.edu Tue Feb 22 14:05:46 2011 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 22 Feb 2011 14:05:46 -0500 Subject: (cba:news) cba target stars In-Reply-To: References: <4AFDFB14-CD3B-49BC-AFFA-5492EBA08BD4@uhu.es> <566766.43378.qm@web30504.mail.mud.yahoo.com> Message-ID: <4D64090A.60004@astro.columbia.edu> Dear CBAers, Thanks for all that great coverage recently! Arto's spell of good weather has been amazing, and of course a winter target at high declination is very well-suited. So the coverage of SDSS1339+48 has been superb. Shawn Dvorak (CBA-Orlando) has also provided a lot of critical coverage (Europe has actually dominated over the USA for this star). I attach the detrended data for one night of coverage (blend of Arto, Enrique, Shawn). Please ask if you'd like more. ER UMa has also, deservedly, had a lot of great coverage - almost 30 straight days. It shows a very large amplitude negative superhump, which we want to track throughout the observing season. Some of the usual heavyweights (Enrique and Tom) have been the main players on this one. Both stars eminently deserve a LOT more data, and are likely to remain decently bright for a while. The other very well-placed star, which so far has been upstaged by these two, is BH Lyn. That eclipsing star also deserves high priority; in 1995, it showed a prominent superhump, but single-site coverage couldn't distinguish two periods: one slightly longer than Porb, and one slightly shorter. Of course, the interpretation depends critically on which is true! Let's fire away assiduously on this one. In the south and deep south, there's CP Pup and AH Men - both stars presently flashing very distinct waves in the light curves gathered by Bob Rea. But I'm very concerned to get light curves from other longitudes - even the southern USA (maybe) for CP Pup, whose short period (90 minutes) might make this possible. AM CVn remains a good target, but I'm inclined to shelve YZ Cnc. My analysis of this star is far from complete, but I suspect it won't yield answers while competing with all these other known-to-be-worthy stars. joe -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: uma613.z URL: