From jop at astro.columbia.edu Sun Jun 8 08:24:00 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 08 Jun 2014 08:24:00 -0400 Subject: (cba:news) stars for the solstice Message-ID: <539455E0.7040609@astro.columbia.edu> Hi CBAers, Getting back in the saddle here after three weeks gobbled up by end-of-school-year, observing run, AAS meeting, even a Camp Uraniborg 40th year reunion. And one more meeting (SAS/AAVSO/CBA) coming up in a few days - where many of us (15?) will get together in California. Just to get you thinking in advance... an issue I'd like to clarify there is: how to make our data available to others in a convenient and transparent way. David Boyd's paper on V1432 Aql, to be given at the SAS, has made me want to pull the trigger on this *now*. It's as good a paper as I could have done, or better - but it took a few rounds of correspondence and some persistence to shake the data loose from us. We have to set up an easier access - including, I think, access by people we don't already know. The AAVSO is the natural channel for this. To be discussed! STARS FOR THE SEASON. STARS TO RETIRE: HS1813+6122, HP Lib, V1084 Her. We have enough! Also AM CVn and T Pyx; effectively, the Sun has already retired them - but just to make it official for these old friends of ours. GW Lib and V355 UMa also should retire, victims of sunlight and neglect. NR TrA also in this category, because the coverage (mainly from Berto, Gordon, Bob Rea, and Simon Lowther) has been so good. DQ HER STARS. Some quite nice targets of this type, and easy to observe since they're bright (mostly 13.5-15.5) and don't *require*, though they *like*, long runs. V1223 Sgr, IGR J17303-0601 and DQ Her itself are very good targets - and others, seasonally appropriate, from Koji Mukai's intermediate-polar webpage: http://asd.gsfc.nasa.gov/Koji.Mukai/iphome/iphome.html NY Lup, V2306 Cyg, RX J2133+51, and V2069 Cyg all need work. I list all these in order of what I'd judge as decreasing priority (i.e. V1223 Sgr as highest priority) - but the stars occasionally flash unexpected phenomena (low states, period changes) which make any assessment of priority very rough. SUPERSOFT BINARIES, or kissin' cousins. Those are: V Sge, V617 Sgr, and WX Cen. We need to study the orbital light curves; but after you get a few orbits, and for sure a few eclipses, you can move on. The main interest here is study how this (the eclipse time, and orbital light curve generally) changes over the years. The orbital periods appear to change rapidly - and there is still no understanding of *why*. RECENT CLASSICAL NOVAE. You bet! My #1 fascination in recent years - I guess since BK Lyn amazed us by announcing itself as a 2000 year old nova. It'd be wonderful to know how the orbital light curves of novae change with the years after outburst - when the hot white dwarf should be cooling down from a half million K. Nobody knows the rate of this cooling, but I believe we can find out by tracing the evolution of the orbital light curves. For this purpose, there are now some great novae available in the sky: V1974 Cyg, V1494 Aql, V1500 Cyg, V4743 Sgr, and V339 Del lead the cavalcade. I'm also pow'f'l curious about V630 Sgr (N Sgr 1936), but I imagine it's too faint for CBA scopes. WEIRD STARS. The best for last. V418 Serpentis! As many of you know, we've mostly steered away from dwarf novae in recent years; there are so many of them, and we've observed >100 of them in their outbursts (so, as a class, their novelty is declining). But some stars are just too weird to resist. V418 Ser might be such a star; its 64 minute period is too short for a hydrogen-rich star, and too long for a helium-rich dwarf nova - or at least will require some tinkering with the theory for such things. (The reason is that there's a P-root-rho relation for the lobe-filling secondaries, and the densities appropriate to helium and hydrogen should be quite distinct.) The star is now at ~17th mag, but try to follow it as far as possible into the muck. The usual time series, as long as possible. BRIGHT AND/OR EASY STARS. Some readers of these pages have small scopes, or have just recently started time-series photometry. Relatively bright or "easy" (large-amplitude periodic signal) stars might then be the most suitable. V339 Del, V Sge, V1223 Sgr, and FO Aqr are good choices. SAME COMPARISON STAR! Just a reminder to keep the same comparison star. It's helpful when everyone uses the same comp star, but not super-important. What matters most is that you choose one and stick with it. Many stars in this note. But as usual, fidelity to one star tends to be a winning strategy, except possibly for the DQ Hers. This means that cba-chat communications about your chosen targets are very useful - because very long time series (possible only for distant telescopes) are absolutely optimum for period-finding on this rotating planet of ours. For most targets, the rewards diminish after 3-4 weeks; I'll try to improve my promptness in demoting stars, but you might want to adopt that timescale as a sort of default value. I've learned a lot from the recent cba-chat flurry triggered by Tonny Vanmunster. Thanks for sending all that stuff... and anything you can do to lure Tonny back from his exoplanet interlude would be great for the CBA! joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Jun 14 22:17:14 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 14 Jun 2014 22:17:14 -0400 Subject: (cba:news) ASASN-14cl: very bright (V=10.7) CV candidate detected by ASAS-SN In-Reply-To: <1544223028.115606934.1402761448298.JavaMail.root@telenet.be> References: <1544223028.115606934.1402761448298.JavaMail.root@telenet.be> Message-ID: <539D022A.9020500@astro.columbia.edu> There's an ancient rule that says the most fascinating outbursts occur during scientific meetings, when astronomers aren't near their telescopes. Holds true again. Seemingly a great target, and very much wanting multi-longitude coverage, since the position is a tad off-season (2155+26). Of interest partly because it's a first-ever-recorded outburst, partly because the range of brightness is so high (8 mag)... but mostly because it's so bright. Dwarf novae (assuming that's what it is) are standard candles, so this dwarf nova would be quite nearby. The nearest stars teach us an awful lot! INcluding: how near they are. joe -------- Original Message -------- Return-Path: X-Mailman-Version: 2.1.14 Precedence: list Reply-To: cba-chat at cbastro.org List-Id: CBA chat List-Unsubscribe: To: "ASASSN" Sent: Saturday, June 14, 2014 5:52:56 PM Subject: [vsnet-alert 17376] ASASN-14cl: very bright (V=10.7) CV candidate detected by ASAS-SN ASAS-SN has four V-band detections of a very bright transient source Name RA Dec Discovery V --------------------------------------------------------------------------- ASASSN-14cl 21:54:57.62 26:41:16 2014-06-14.52 10.66 Very bright CV candidate, V>16.0 on 2014-06-13.5, V=10.7 on 2014-06-14.52 (four detections in two cameras), matches to g=18.8 blue SDSS star No previous outbursts in CRTS data, but some variability present. ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/