From jop at astro.columbia.edu Wed Aug 19 07:13:24 2015 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 19 Aug 2015 07:13:24 -0400 Subject: (cba:news) stars for late August Message-ID: <55D464D4.3000907@astro.columbia.edu> Dear CBAers, We're done with V1315 Aquilae for the year (probably for several years) - and also done with CP Lac, whose light curve was really disappointing. Here are my recommendations for northern targets this month: 1. WZ Sge. Strangely, we've never done a campaign on this ultra-famous star in quiescence. Serious oversight. There's an intruder star 7 arcsec away, so you have to figure out what to do about that (probably exclude it... depending on how good your drive is). It's about 15.5, though it has a few excursions to 14.5, which would be awfully fascinating to catch in the act. 2. LS Peg. Good target for the smaller scopes - or for the bigger scopes when ambition is flagging. 1-2 minute integrations are fine (as are faster, if you prefer). 3. V1974 Cyg. I think about 17.5 now. We need another season's coverage to establish a good ephemeris extending back to the 1992 eruption ("nova of the century"... and since they waited until 1992 to say so, they can't be accused of jumping the gun). 4. LQ Peg. We've logged just one brief campaign. Rude & Ringwald have presented some nice results, and it's time to put some intense effort into this star. I'd rate it as about to equal to LS Peg in priority... but the first few nights will probably clarify this. 5. V1500 Cyg. This is a 19th mag star, but if you like faint stars, this is your guy, with a 1-mag amplitude. We're trying to pin down the exact period over the long haul (back to 1975), so just one or two good nights will be fine. 6. V Per = Nova Per 1889. You can't blame a guy for trying. I think about 18.5 and eclipsing. We want to know *everything* about this short-period eclipsing old nova, which importantly impact almost everything we do (the CBA, not the world). Sorry about the magnitude, and I know it's wishful thinking, but I thought I'd give it a try. As usual, the best observing practice is to adopt a star and stick to it - *density of observation* is very critical. Until you don't like it any more - then adopt a different star. In the south, there are three old novae I'd recommend. They're all difficult targets (faintness and crowding) but would be great to study thoroughly: V728 Sco, V4743 Sgr, and V630 Sgr. We have some data on all them, mainly from Gordon... just enough to whet my appetite. Plus CD Ind, an asynchronous polar we're studying long-term (slow synchroniztion of rotational and orbital periods). Good target, not faint. The big T Pyx paper is almost complete. Attached is a draft of the paper, though really you should just pay close attention to the author list and the separate observing log. (BTW the stuff at the back is pure gobbledygook.) I just would like them to be as accurate as possible - check 'em. Also, most journals want both postal and email addresses for authors, so send 'em, if you haven't done so recently (and cc to Jonathan: jk at 155west.org) joe -------------- next part -------------- A non-text attachment was scrubbed... Name: tpyx818.odt Type: application/vnd.oasis.opendocument.text Size: 62010 bytes Desc: not available URL: -------------- next part -------------- A non-text attachment was scrubbed... Name: tptables.odt Type: application/vnd.oasis.opendocument.text Size: 21219 bytes Desc: not available URL: -------------- next part -------------- ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Wed Aug 19 12:41:35 2015 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 19 Aug 2015 12:41:35 -0400 Subject: (cba:news) V380 oph Message-ID: <55D4B1BF.3020201@astro.columbia.edu> Oops, I forgot about V380 Oph in yesterday's message. V380 Oph has been in a low state for months (all year?), and these low states of VY Scl stars can teach us a lot about the secondary stars and processes. Gordon has got in some nights from Australia -= enough to demonstrate that the orbital signal dominates the light curve. But it makes a big difference whether we see just one hump per orbit, or two. One => probably a reflection effect, indicating a very hot WD. Two => possibly the secondary star alone, with an "ellipsoidal" variation. If you can do 19th mag (sorry), let's gang up on the star and torture it for its secrets. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Aug 29 18:40:01 2015 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 29 Aug 2015 18:40:01 -0400 Subject: (cba:news) september stars - a big menu Message-ID: <55E234C1.9050107@astro.columbia.edu> a plain-text file (I'll send pdf if you can't read it) joe -------------- next part -------------- Aug. 29, 2015. Hi CBAers, Very good coverage in recent weeks. Some of the targets are ready to retire: LS Peg. *Great* coverage of this bright and very active star. Unfortunately it seems to be reliuctant to cough up any of its secrets to time-series photometry. Time to quit, I think. WZ Sge. I had great hopes for this star, but the first week's coverage was not encouraging. Lots of action - a beautiful light curve, considering its faintness. But no new periods. At most, we'll revive it next year, And some almost ready to retire: LQ Peg. Very impressive light curve, and worth continuing for at least another week. Just a single period (2.99 hrs) evident so far, but hints that some more subtle structure may emerge with more work. V380 Oph. Thanks mainly to Gordon and Bill Goff, we now have an apparently *orbital* light curve of this very faint (19th mag) star. The orbital period is different from the published period, but the difference indicates that the published period is an incorrect selection of an alias (so ours is correct). The precise value of Porb is of no special interest, but the shape of the light curve suggests interpretation as a heating effect - heating of the secondary by the hot white dwarf, with very little contribution from the accretion disk (if any). Nice! Just a few more nights would wrap up our work on these two stars. For LQ Peg, it would be best to do that *now*; for V380 Oph, waiting for excellent observing conditions might be smart. OLD NOVAE We're getting great results on old novae, and there are lots in the July- October time window. 1. QU Vul (N 1984). Still at 15.5, and a short-period eclipser. Made to order for CBA coverage! A top priority target. 2. V1974 Cyg (N 1992, "the nova of the century"). Mag 17.5, and a harder target. We need one more season to complete our study - where "season" could be as little as 7-10 days if we could get *dense* coverage. 3. V630 Sgr (N 1936). Anothrer short-period guy which has escaped our attention in the past. I think qbout 17 (but I dunno). 4. V Per (N 1887). Another short-period and deep eclipser. At 18.5, it's an ambitious target - but is likely to yield big rewards if you handle the magnitude NOVALIKES 1. HV And. A 15-16 mag star which has been strangely negkected for many years. Fred Ringwald has found it to be a new SW Sex star, and those have become a specialty of ours. Let's do it. 2. QR And. An eclipsing supersoft source, apparently with a Porb rapidly increasing. We need a few eclipses in 2015. 3. AQ Men. Somewhat out of season, but at -80 degrees, the season is really long. Josch Hambsch is getting steady coverage from Chile. 4. ES Cet. Need some more runs on this helium star, to test GR as the driver of mass transfer. 5. CD Ind (an asynchronous polar). Rapidly oscillating between ~17 and ~19 - pretty wild changes. The cba-chat messages from Gordon tell the story. Not entirely new for this star, but much more extreme than anything in the record. Worth continuing! Lots of targets. As usual, your observations are likely to have the most impact if you adopt a favorite star and stick with it. joe BTW a remark on comp stars. It's definitely best if you keep the same comp star fro all your observations - assuming your original choice is halfway decent (nothing too red, too crowded, too faint). This is especially true if your photometry is unfiltered, because unfiltered magnitudes can't be put on a standard scale anyway. If you do change your comp star, make it obvious in big fluorescent letters. -------------- next part -------------- ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/