From jop at astro.columbia.edu Sat Dec 2 13:37:51 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 2 Dec 2017 13:37:51 -0500 Subject: (cba:news) orbital light curves of novae Message-ID: Dear CBAers, We have enough now for V Per and QZ Aur. Lots of eclipses, and sufficient coverage around the orbits to define the shape very nicely. These are pretty faint stars. I was very surprised to see what a good job you guys can do with them - basically *better* than is done with 2-4 meter telescopes. The latter have much higher signal/noise PER POINT, but because they are also tainted by flickering, the persistent orbital light curve is MASKED. The CBA light curves are quite superior in defining the mean shape... and that shape is one of the keys to understanding the structure of the binary. These comments apply mainly to old novae. The dwarf novae are a different story; since they wander between high-, low-, and medium-accretion states, the "average" light curve is not well-defined. Anyway, for us, it's worth stressing: Frequent long-night coverage of old novae is a great project - including even the recent ones. "Old" meaning at least, say, 3 magnitudes down from max... but it's not impossible that interesting periodic signals could be found even near max. Seasonally appropriate old novae are: V959 Mon, T Pyx, CP Pup, RR Pic, and DN Gem. As usual, it's best to pound one of them senseless... rather than scattering the coverage. Other stars. We're quitting on WZ Sge. Another 1-2 weeks is probably goof for FO Aqr, but not after that. And I think AO Psc is done for the year, too. joe For rhe DQ Hers, I especially recommend HZ Pup, HT Cam, and DW Cnc. But as usual, we *always* like timing observations of DQ Her stars. ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Mon Dec 4 21:49:17 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 4 Dec 2017 21:49:17 -0500 Subject: (cba:news) BT Mon and the nova project Message-ID: <15fd0dfd-3b42-5280-39fb-7b6a4485b5bb@astro.columbia.edu> Hi CBAers, Just to remind, BT Mon is a 1939 nova which shows deep eclipses with an 8.01 hour period. There are no published orbital light curves - because of the coincidence with the Earth's spin period. But we can do it, because we span a range of longitudes. In addition, it looks now like the star's period is changing on a surprisingly short timescale... so many observations around mid-eclipse would be nice. (We need more than a few, because it's quite faint at mid-eclipse - so some averaging is needed.) The eclipses are now occurring around JD xxxxx.72, so they're visible at eastern USA longitudes, and will be in the western USA in about a month (as the "0.01" part gradually accumulates!). That means it will soon be visible also in Australia, where we have two great observers (Gordon Myers and Greg Bolt). Not in Europe - but we need coverage of the other half of the orbit too (the part no published work has ever covered). Part (most?) of the reason I'm keen on this is that the eclipse timings *so far* indicate a large decrease in the orbital period. Conventional CV evolution theory has the period decreasing pretty fast around P = 8 hours - but it has never been observed. It probably takes an eclipsing system - and one with a 30-year baseline - to test it, because only such a star would offer the needed precision. There are only ~3 such stars, and BT Mon is one. Now let's see how it goes. BTW this is a star where you can't really cheat the "<2 airmasses" rule of thumb. As a star of long Porb, BT Mon's significant variations (eclipse-related and other) are slow-ish... and that means they're too easily confused with differential-extinction effects. OK, maybe on good nights you can cheat a *little*... at least if you list the airmass in your data submission (which enables me to approximate a correction for differential extinction). But watch out. joe p.s. also, fear not if your signal-to-noise at mid-eclipse is abysmal. The time of med-eclipse is really determined by the data approaching and following mid-eclipse. Mid-eclipse itself is flattish and uninformative. ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Tue Dec 5 17:15:02 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 5 Dec 2017 17:15:02 -0500 Subject: (cba:news) FO Aqr, finis at last Message-ID: <13a34006-8822-21a1-b865-cdc817a60efe@astro.columbia.edu> Hi CBAers, Finally we can declare an end to this year's FO Aqr campaign! Short tuns, differential extinction, trees... let's face reality and say goodbye to Aquarius for the year. Novae and DQ Her stars (intermediate polars) dominate the menu now. But ES Cet is still quite a good target. joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Tue Dec 5 17:15:02 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 5 Dec 2017 17:15:02 -0500 Subject: (cba:news) FO Aqr, finis at last Message-ID: <13a34006-8822-21a1-b865-cdc817a60efe@astro.columbia.edu> Hi CBAers, Finally we can declare an end to this year's FO Aqr campaign! Short tuns, differential extinction, trees... let's face reality and say goodbye to Aquarius for the year. Novae and DQ Her stars (intermediate polars) dominate the menu now. But ES Cet is still quite a good target. joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri Dec 8 18:50:02 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 8 Dec 2017 18:50:02 -0500 Subject: (cba:news) Fwd: Observing campaign on TT Ari In-Reply-To: References: Message-ID: <23e6e9b7-3766-1550-fb22-4feb0325ad8d@astro.columbia.edu> Hi CBAers, Over the next ~5 days or so, Deanne and Christian will be studying TT Ari intensively at radio (and likely other) wavelengths. At 11th magnitude, it's the world's easiest target. I'll write when the exact times of observation are known; but any pobservations over the next week will be helpful. joe p -------- Forwarded Message -------- Subject: Observing campaign on TT Ari Date: Mon, 4 Dec 2017 21:45:18 +0200 From: Deanne Coppejans To: Joe Patterson CC: Christian Knigge Dear Joe We have an AAVSO observing campaign on TT Ari over the next two weeks (https://www.aavso.org/aavso-alert-notice-608 ). I was wondering if you could alert the CBA to it please? The campaign is to get high cadence, multi-wavelength observations of TT Ari to determine the source of the flaring radio emission. In particular we have two 4h epochs of VLA observations of TT Ari over 10-12 December. The exact time and date are not set yet, and we will only know these two days in advance. I will announce the time on the AAVSO campaign forum and will let you know as soon as we know the exact time. In particular, we are looking for strictly simultaneous photometry in a range of bands (as high cadence as possible). Thank you very much for your help. Best wishes, Deanne -- Deanne Coppejans Postdoctoral Associate Northwestern University ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Dec 9 05:06:06 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 9 Dec 2017 05:06:06 -0500 Subject: (cba:news) Observing campaign on TT Ari In-Reply-To: References: <3ff5a288-1232-a0c9-ee0c-910eb8486d72@astro.columbia.edu> Message-ID: Here is the updated information on TT Ari. In other words, highest priority starting right now! joe p.s. Deanne, you should send any updates directly to cba-news at cbastro.org On 12/9/2017 3:43 AM, Deanne Coppejans wrote: > Hi Joe > > Thank you so much. The observations are planned for 2 - 6 UT on December > 10 and December 11. This is still queue-based observing though, so > there's a chance that the observations could start later (a start time > of up to 3.30 UT). The weather is looking good for then, but if it turns > then the observations will be rescheduled to 12 December. > > Best wishes, > Deanne > > On Sat, Dec 9, 2017 at 1:51 AM, Joe Patterson > wrote: > > Hi Deanne, > > Sent the alert out just now.? Let me know if the observation dates > become more precisely known! > > joe > > > On 12/4/2017 2:45 PM, Deanne Coppejans wrote: > > Dear Joe > > We have an AAVSO observing campaign on TT Ari over the next two > weeks (https://www.aavso.org/aavso-alert-notice-608 > ). I was > wondering if you could alert the CBA to it please? > > The campaign is to get high cadence, multi-wavelength > observations of TT Ari to determine the source of the flaring > radio emission. In particular we have two 4h epochs of VLA > observations of TT Ari over 10-12 December. The exact time and > date are not set yet, and we will only know these two days in > advance. I will announce the time on the AAVSO campaign forum > and will let you know as soon as we know the exact time. > > In particular, we are looking for strictly simultaneous > photometry in a range of bands (as high cadence as possible). > > Thank you very much for your help. > > Best wishes, > Deanne > > -- > Deanne Coppejans > Postdoctoral Associate > Northwestern University > > > > > -- > Deanne Coppejans > Postdoctoral Associate > Northwestern University ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sun Dec 10 07:04:16 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 10 Dec 2017 07:04:16 -0500 Subject: (cba:news) AA Dor and T Pyx Message-ID: Hi CBAers, I'm getting close to finishing the IM Nor paper. Only a few CBAers contributed to this one (Gordon, Berto, and Paul Warhurst so far); it's very faint, far southern, and obscure - discouragements to most of us. This paper will go into some detail concerning the irradiation of the donor star by the hot white dwarf, in the aftermath of a nova explosion. I would like to include light curves from a classic supersoft binary and a classic hot-subdwarf binary - stars in which heating effects are truly obvious and well-known. It's hard to convince people of the importance of heating in CVs; some think it's obvious, and others think it's impossible. And I think there's a third group ("maybe true but of no importance"). AA Dor is a very famous star with a beautiful light curve - primary eclipse, secondary eclipse, and sinusoidal wave obviously signifying the heating of the brown-dwarf secondary by the hot-subdwarf primary. It has been analyzed in great detail - it competes with HW Vir as the prototype of the class (sort of like SS Cyg and U Gem battling for the honors among dwarf novae). CBA light curves of AA Dor would be a nice addition to our paper. We already have a beautiful orbital light curve of a supersoft (QR And), and AA Dor would bookend it nicely. It would be a nice primer on heating effects - in a detached binary (AA Dor) and a full accretion-disk system (QR And). At magnitude 11.5, AA Dor is blindingly bright; I recommend a V filter if you have one you like - although unfiltered is OK too if you scrupulously avoid large airmass. As befits a simple star, 6 hours is both the binary period and the right ascension. Nice holiday gift. Ali is the greatest, But now hear the latest: AA Dor Is what we wish for. The holidays have also brought T Pyx back in the sky. Let's get going on this star. Southern USA observers can contribute, as well as - obviously - the australites. Each new season brings peril to our favorite theory: death by heating. joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri Dec 15 22:46:24 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 15 Dec 2017 22:46:24 -0500 Subject: (cba:news) BT Mon and AA Dor Message-ID: Hi CBAers, Thanks for your coverage of these interesting stars. We're done with AA Dor; since it's a "pre-CV" (no mass transfer), there's no flickering - which means not much averaging is needed to amass an accurate orbital light curve. Done! Beautiful light curve. BT Mon is more complicated. The eclipse times are plenty interesting, and suggest quite a large period decrease. But the actual orbital light curve has proved elusive. We have plenty of good-quality eclipses (which I thought would be problematic because of the faintness), but incomplete coverage of other phases. In particular, orbital phases 0.4-0.9 are poorly covered. Because the period is so close to 8 hours, every night is pretty much the same. Each day, the eclipses at xxx.06, xxx.39. and xxx.73; so if you can cover orbital phases 0.4-0.9 on this ephemeris, that'll clinch the full orbital light curve. Just 1-2 weeks of coverage will complete the study. Thanks! joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sat Dec 23 04:19:30 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 23 Dec 2017 04:19:30 -0500 Subject: (cba:news) BT Mon, finis Message-ID: <9cddbebb-5e76-248e-81d8-a94b383e6b99@astro.columbia.edu> Hi CBAers, Thanks for all the BT Mon data. With its period so close to 8 hours, it's not easy to get a full light curve, and in particular to test securely for the presence of a secondary eclipse. (In an edge-on binary of LONG Porb, a secondary eclipse is expected.) I'm not 100% persuaded yet, but a secondary eclipse seems to be absent. Also, the eclipses are coming very early - a full 0.05 P_orb early relative to the existing ephemeris. This needs no "persuading"... and might signify a large period decrease. We'll repeat this next year and see if that trend holds up (when the drift would grow to 0.06P_orb). But we're done for the year. Sorry to inflict such a difficult star on you! Next year it'll be easier, because we'll "know what we're looking for"*. joe p *Ha! ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/