From jop at astro.columbia.edu Fri Oct 16 14:33:06 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 16 Oct 2020 14:33:06 -0400 Subject: (cba:news) IM Nor and friends... plus V392 Per and novae generally Message-ID: <033124df-5872-922a-a647-ca7c32b21921@astro.columbia.edu> Hi CBAers, Our long campaign on IM Nor has ended, and here's what came out: https://arxiv.org/ftp/arxiv/papers/2010/2010.07812.pdf Comments solicited. Submission to a regular journal is still a ways off. Since there's some pretty speculative stuff in there, I've got to sit on that for a little while first. What seems exciting on a Monday can sometimes look pretty spacey by Friday! But I've sure gotten seduced by these novae! (Supersofts too, but there are precious few them in our galaxy.) So here's a list of novae which I think are promising for Oct-Nov observing. V392 Per. Lots of good data from USA observers (especially western USA - mainly Richard Sabo and Waly Cooney). Even more from Joe Ulowetz, and I use his data for calibrating everyone since his location is central in North America. But not much from Europe, which we really need, because the periodic-signal search in this star is TRICKY - we just need to splice together runs over a wide range of longitude. 15th mag, well placed in the sky... and a star which seems destined for greatness (the only dwarf that became a nova! There are some other (now quiescent) novae which are good targets in Oct-Dec. Here they are: V597 Pup, CP Lac, DN Gem, and maybe KT Eri. I don't know much about these - maybe just or two of them really is a good target. Use your judgment. I guess it's too late for V1974 Cyg. But if you can get ~3 hours on this star, that's the best northern target of all. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Oct 17 07:29:47 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 17 Oct 2020 07:29:47 -0400 Subject: (cba:news) CC Scl... and intermediate polars Message-ID: <6e43a500-7625-0818-61ce-08b2ca071322@astro.columbia.edu> Hi CBAers, Oops, I left out our campaigns on intermediate polars; I'll study and comment later on priorities among them (the list is getting big!). Enrique, do you want to chip in re these? And CC Scl. Gordon, Berto, and Josch have done well on this multi-periodic star this year (I think our first big year on it - the periods are still not nailed down). But Josch's coverage in the "Americas" longitude is low time resolution, and some North American observers - definitely Walt Cooney & Richard Sabo, and likely others - can get good coverage of this 17.0 mag star at high time resolution (~1 minute). Not for very long (Sculptor!), but some 3-hour runs at good time resolution would break aliases and reveal the true underlying period structure. [OK, Richard's off the hook* - Montana! - but southern USA should be good. (*On second thought, only if he votes for Steve Bullock.)] For those of you new to the CBA, breaking the 24-hour alias problem is one of our prime reasons for existence. You just can't nail down periods from observations at a simgle longitude (as I spent the first 10 years of my career learning). There's so much WATER in the southern hemisphere!...and many studies of periodic behavior in southern stars suffer from this uncertainty. joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Oct 31 06:05:26 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 31 Oct 2020 06:05:26 -0400 Subject: (cba:news) novae, near and far Message-ID: <263760f9-1668-f925-46fe-0578fa7a3750@astro.columbia.edu> Hi CBAers, Congrats to Tonny and Damien for spotting that amazing nova - it even humbles T Pyx! - in M31. And with bright moonlight, along with so much contaminating starlight. I don't hold out much hope for extracting our usual secrets - periods - from this star. It did make me wonder if we can possibly get periods from the supersoft sources (more or less "permanent novae", since they're white dwarfs burning H on the surface all the time)) in the Magellanic Clouds. Especially CAL 87, the prototype in the LMC. We've learned a lot from our studies of such stars in the Milky Way, but they're very few, because of interstellar absorption in our galaxy. Maybe Gordon can take a crack at CAL 87...? The main problem, of course, is CROWDING... and every distant star presents its own complicated story of meddlesome neighbors. Meanwhile, back at the Milky Way ranch, there are plenty of novae inviting time-series study. The recent guy is V392 Per. Richard Sabo has been doing great work on it, but we're really hurting for European coverage. There is a lot of variability in this star - especially for a recent nova - and periods are hard to extract amid all the noise (in the star!). It needs more attention from all longitudes. At 15th magnitude in Perseus, it should be an easy target. LONG time series are especially valuable. This star - the only nova in history to rise from a previously known dwarf nova - deserves your attention! We're also about to write something up on V Per, the 2.5 hour deep-eclipsing nova of 1889. Lew Cook has been getting some great data on this 18.5 (diving to near 20 in eclipse) mag star. But this too needs coverage at other longitudes, in order to search for variability on other timescales. It also needs more North American coverage. Similar story for V597 Pup, although it's a newcomer to our menu: 18th magnitude eclipsing nova (of 2007), seemingly also an intermediate polar. This may become our top southern target of November-january. There may be an intruder star just to the south of the nova... but give this one a try (if Puppis is in your sky), it has promise of a great return. Finally, there's the Gemini twins... not Castor and Pollux but DM and DN Gem, two decently bright and well-placed novae with essentially no period information known. We've never even given them a try. Let's see if we can add to humanity's sparse knowledge of these stars. We have some new observers this year, so let me stress again the value of LONG observations (>4 hours if possible, or even longer). Because all CVs have erratic variability, long observations give the best chance of overcoming that and revealing a true period - rather than one which is merely an accident of the observing window. The main qualifier* is: avoid high airmasses (airmass 2.0 is borderline). joe p * But there's one circumstance where you can, and perhaps should, get braver. If you're in a multi-longitude campaign and suspect that you're the main observer at your longitude, you can cheat to maybe 2.5 airmasses or so. I've learned how to correct accurately for such "venial sins"... and extending the longitude range of our campaigns is important. Above airmass 2.5, things get pretty terrible. ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Oct 31 06:26:21 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 31 Oct 2020 06:26:21 -0400 Subject: (cba:news) V378 Peg versus V392 Per Message-ID: Short addendum to my note just sent. These two stars (hard ro keep straight: V3xx Pex) have been getting most attention of our northern observers this month. But we're almost done with V378 Peg - your basic novalike variable with nice superhumps (no quirks/frills/temptations that I can see). If you're looking for a nice 15th mag novalike for a long time-series observation during November/December, V392 Per is the way to go! joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/