From jop at astro.columbia.edu Tue Nov 3 14:33:34 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 03 Nov 2009 14:33:34 -0500 Subject: (cba:news) TT Ari take 2, or even 3 Message-ID: <4AF0858E.3000600@astro.columbia.edu> Dear CBAers, Today's messages from Tom, and Ivan Andronov, establish that TT Ari has dived low again - maybe even (very transiently) to its full low of V~16. This makes the situation kind of murky. I was just about to suspend the campaign, since the light curves around V=13, where the star has been dallying, look very complex - hard to decipher. But after just looking at Tom's light curve... that crazy huge-amplitude signal around 0.35-0.40 d is back! This is emphatically a GREAT target in the days to come. That mysterious signal maintained pretty good coherence for about a week; and if it does so again, then we can bridge the gap to see if the underlying signal is truly phase-stable. So please rev up your engines again for TT Ari! Most of you will probably want to do V or clear photometry, in an attempt to get good time-resolution (in addition to the 0.4 d signal, there are very fast and very large variations). Back to the light curves. Another message soon... joe From jop at astro.columbia.edu Tue Nov 10 13:24:45 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 10 Nov 2009 13:24:45 -0500 Subject: (cba:news) TT Ari in its darkest lair Message-ID: <4AF9AFED.50400@astro.columbia.edu> Dear CBAers, Some amazing light curves of the quiescent TT Ari coming from the western USA observers, plus Mike Potter in Maryland who has managed to extend the coverage by 2-3 hours to the east. I'm still hoping for good things from Europe, but I fear that weather there has turned bad - except for Enrique Agustino (Spain) who has been waging a heroic struggle with a 4-inch telescope (I think!). Just a little, so far, from NZ and AU, but hope springs eternal there too. I've never seen anything like these light curves. In fact, no one has - not for TT Ari, and not for any other CV. About 7 out of every 11 hours, the star is down at V=16.3, and shows the ORBITAL period - for the first time ever. There is then no activity, just a "heating" light curve which is likely the result of the hot WD illuminating the secondary's face. Then the star goes into convulsions at V~15 for 4 hours, then rests again... to repeat the cycle about every 11 hours. Just flat astounding. So far, we've learned more from the V (or, if you can't spare the photons, clear) light curves than from the multicolor photometry. But that's probably because it has been at true quiescence for only 1 week. Fortuitously I'm about to leave on an observing run with the 2.4 m telescope; if weather permits, I'll spin filters and likely deconvolve this star into M dwarf and hot WD. The flickering itself, when it's there, is broadband and not too likely to cough up much information from multiband observations. I slightly recommend choosing one filter and sticking with it. Also, there's value in preserving your setup as much as feasible; I've had enough simultaneous coverage to calibrate the various observers. I say "slightly recommend" because this is in the absence of real knowledge about what we are observing. A year from now, I'll have a more definite opinion about how we *should* have observed it! More info about other stars tomorrow. Is there help on the way from other longitudes re TT Ari? It would be great - the coherence of this 11 hour cycle is far from established, and it's a damn tough periodicity to evaluate! joe From jop at astro.columbia.edu Thu Nov 12 15:57:56 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 12 Nov 2009 15:57:56 -0500 Subject: (cba:news) TT Ari in trouble Message-ID: <4AFC76D4.1060304@astro.columbia.edu> Or more correctly, our campaign. The weather in the southwestern USA has "gone south" (forgive the parochialism), and will probably stay bad for another 3 days. We really, really could use help from other longitudes! Or latitudes. The eastern USA is getting battered by a slow-moving storm... so I hope that other observers can carry this forward! We did get NZ coverage last night from Bob Rea and Bill Allen. The star remains more or less in that strange state I described... but it will be a challenge to sort out the period/quasi-period of the huge humps - given the unhappy P_rot and sometimes unhappy weather of our own planet. What about the great expanses of Europe and Australia? joe From jop at astro.columbia.edu Thu Nov 12 23:53:05 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 12 Nov 2009 23:53:05 -0500 Subject: (cba:news) when not to love your filters... In-Reply-To: <002801ca63de$7a0ea4b0$0600000a@Main> References: <4AFC76D4.1060304@astro.columbia.edu> <002801ca63de$7a0ea4b0$0600000a@Main> Message-ID: <4AFCE631.5090702@astro.columbia.edu> Hi Terry et al., This is a good opportunity to comment on filters... though it's somewhat specialized to TT Ari. Because of the star's extremely strange and unprecedented state - with cool secondary and hot WD dominating in the non-flaring phases - it really is true that multicolor data can be of enormous help in decoding the relative contributions to the light. (And this is rare: most CVs, i.e. their disks, are so broadband that there is seldom much advantage in using filters.) However, this presupposes that the multicolor data has high statistical accuracy... and there is practically no chance of achieving that with small telescopes on a flickering 16th magnitude star. So one lesson is a general one: improve S/N by observing clear (or roughly clear; a little blue block can help with differential-extinction issues). This is almost always optimum for period-finding issues... and shortening exposures to ~60 s will help with time-resolution and possibly data quality (if your drive is problematic). But here's an important consideration that cuts the other way. This is a landmark event in the history of humanity's acquaintance with TT Ari. The light curves are something I've never even dreamt of; and here they are, rolling off our little telescopes. Since TT Ari is the brightest CV in the sky, that's nothing to sneeze at. So our observations have solid archival value - except for unfiltered data, which doesn't, since the bandpass is not defined. Personally I tend to prefer data of high statistical quality (unfiltered), since that helps me get science from it in the short run; but I could imagine filtered data being equally or more productive for other studies down the road. For brighter stars and/or bigger scopes, V has much to commend it, because it is excellent (ideal) for archival purposes, has low extinction, and you can often get decent S/N. (Of course, if our stars weren't rapid variables, we could always get a desired S/N by just observing longer... but we don't have that luxury!) Sorry for going on so long... but in my opinion, 300 sec is too long. When the star flares, significant changes take place in 300 sec. Anything over about 120 s is difficult to recommend for CVs, unless you know - as we never do - that no rapid state changes are occurring. Fortunately, some CBAers ignore my advice and observe in V. That greatly helps in calibration. If everyone observed unfiltered, our calibration would be really pathetic. For people who have been observing this star for a while now, I don't recommend changes in filters or comp stars. I've measured the offsets between different observers; and while they change slightly (and somewhat inexplicably) from night to night, they are of great use in splicing light curves. If you do change, announce it prominently in the message! joe Terry Bohlsen wrote: > I took 2 hours of R filter data last night from the east of Australia before > it clouded in. > Hopefully this will help a bit. > What exposures are OK? > I tried 120 secs and 180 secs but the SN is still a bit low. Is a 300sec > exposure too long? > > Cheers > > Terry Bohlsen > Armidale NSW > Australia From jop at astro.columbia.edu Fri Nov 13 17:29:49 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 13 Nov 2009 17:29:49 -0500 Subject: (cba:news) [Fwd: GALEX observations of TT Ari] Message-ID: <4AFDDDDD.7010000@astro.columbia.edu> Dear CBAers, Galex (an ultraviolet imaging/spectroscopy satellite) has scheduled some target-of-opportunity time for TT Ari, from now until Nov. 27. Appended is the schedule. Like nearly all science satellites, this is a low-Earth-orbiter, hence the windows are all somewhat brief - but there are many of them, and if you have clear sky coinciding with any of these times, your observations will have very high scientific value. Under these circumstances, it might well be best to use filters, to get truly simultaneous measures of the continuum. (Hard to say for sure, though; we'll know for sure after the data are in!) joe -------- Original Message -------- Subject: GALEX observations of TT Ari Date: Fri, 13 Nov 2009 10:45:15 -0800 From: Karl Forster To: jop at astro.columbia.edu CC: Karl Forster , Chris Martin , kerry.d.erickson at jp.nasa.gov, susan.g.neff at nasa.gov Hi Joe, It was good to see you again. Thank you for sending the request for directors discretionary time for observations of TT Ari. I agree, it is a unique chance to explore this CV in a "zero accretion" state. With Chris's approval I have scheduled some GALEX observations of TT Ari for next week and will continue with more observations until we loose visibility on November 27th. Here is the schedule of observations: Eclipse Target_ID Survey OW_pos Start End Exposure (seconds) 34933 TT_Ari ETI imaging 2009-11-14T18:26:41.2Z 2009-11-14T18:51:24.2Z 1480 34940 TT_Ari ETS grism 2009-11-15T05:53:58.5Z 2009-11-15T06:21:33.1Z 1650 34941 TT_Ari ETS grism 2009-11-15T07:32:32.6Z 2009-11-15T08:00:08.6Z 1650 34954 TT_Ari ETI imaging 2009-11-16T04:53:55.4Z 2009-11-16T05:21:48.1Z 1670 34955 TT_Ari ETI imaging 2009-11-16T06:32:29.5Z 2009-11-16T07:00:23.3Z 1670 34969 TT_Ari ETI imaging 2009-11-17T05:32:26.8Z 2009-11-17T06:00:34.9Z 1680 34970 TT_Ari ETI imaging 2009-11-17T07:11:00.9Z 2009-11-17T07:39:09.9Z 1680 34983 TT_Ari ETI imaging 2009-11-18T04:32:25.0Z 2009-11-18T05:00:44.0Z 1690 34984 TT_Ari ETI imaging 2009-11-18T06:10:59.2Z 2009-11-18T06:39:18.9Z 1690 34998 TT_Ari ETI imaging 2009-11-19T05:10:58.8Z 2009-11-19T05:39:26.3Z 1700 34999 TT_Ari ETI imaging 2009-11-19T06:49:33.1Z 2009-11-19T07:18:01.0Z 1700 35013 TT_Ari ETI imaging 2009-11-20T05:49:34.5Z 2009-11-20T06:18:07.4Z 1710 35014 TT_Ari ETI imaging 2009-11-20T07:28:09.0Z 2009-11-20T07:56:42.1Z 1710 Note: All time are UT I also wanted to let you know that there have been a number of GALEX exposures of TT Ari earlier in the mission: Date Survey Target_ID Exposure 2003-11-22 AIS AIS_184_sg44 144s 2004-11-19 GII GI1_113009_TT_ARI 1467s 2004-11-19 GII GI1_113009_TT_ARI 1686s 2005-10-06 AIS AIS_184_sg44 112s (NUV only) 2005-11-02 AIS AIS_184_sg44 106s 2007-10-16 AIS AIS_184_sg44 106s 2007-11-04 AIS AIS_184_sg44 96s Note that the GI observations were centered on the position of TT Ari but the All sky survey observations placed the star approx 20 arcmin from the center, still well within the field of view. I noticed that the GI observations have a reflection feature in the NUV exposure due to a star off the south edge of the field of view. To avoid this I have moved the pointing center for the new observations 10 arcmin north. So TT Ari will be 10 arcmin south of the center of the field of view. I have also included a couple of grism exposures with dispersion angles (PA East of North) 320 and 180 degrees. This will avoid confusion with spectra from some of the nearby bright stars. All the archive data is available at MAST: HTTP://galex.stsci.edu/GR4/ except for the photon data which you will need if you want to explore variations during an exposure (in the archived and new data we will take). Let me know if you have any questions or need more information. thanks Karl From jop at astro.columbia.edu Sat Nov 14 20:18:24 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 14 Nov 2009 20:18:24 -0500 Subject: (cba:news) TT Ari tonight Message-ID: <4AFF56E0.5070708@astro.columbia.edu> Dear CBAers, Reminder: Galex will observing TT Ari TONIGHT from 0553->0801 UT - perfect for USA observers. They will be using their grism spectrograph, so this particular night is a good one for using filters - assuming you have a clear sky. Of course, the usual time-series is plenty good too. Kitt Peak, and the southwestern USA generally, continues to suffer from clouds and fog. No stellar photons have been seen here in 2.5 days. We probably be wrapped in another fog bank tonight... but you lowlanders might be able to get something. I've been using the time to prepare spliced light curves so far in this very-low state, and would happy to send 'em to anyone who would like 'em. The star will remain on the Galex menu till Nov. 27 - but only tonight for spectroscopy. joe From jop at astro.columbia.edu Wed Nov 18 03:57:26 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 18 Nov 2009 03:57:26 -0500 Subject: (cba:news) introducing xss0056 In-Reply-To: <4B03988E.7060101@astro.columbia.edu> References: <20091118031615.4AC3C1B47E@carrera.xpressweb.com> <4B03988E.7060101@astro.columbia.edu> Message-ID: <4B03B6F6.9050202@astro.columbia.edu> Dear CBAers, Pardon me for exceeding the legal limit (for the chatters), but I wanted to promote a star I just started to observe last night. That is XSS00564+4548... which I started in on after I saw that the CBAers were doing a fully adequate job with TT Ari from this longitude (western USA; we still ache for other longitudes). This appears to be a DQ Her star with twin pulses around 8 and 8.5 minutes, plus some signals at low-frequency (conjectured orbital, plus one other possibly around 30 minutes). Pretty interesting. It's plenty bright (around 14.8), and well placed for very long observation in Cassiopeia. I have consecutive 8-hour nights on it, and am now begging for someone to carry the torch forward. As in... well... this coming night, and thereafter. Densely spaced long time series are precisely what's needed to enable great sensitivity in period searches. The usual CBA routine - unfiltered light, 30-60 s exposures, find a comparison you like and stick with it - will do just fine. There's a little companion roughly 10 arcsec east of the CV, at about 19th mag I think; probably not relevant unless the CV does something funny. You can find a chart and some details in Bikmaev et al., astro-ph 0603715. The TT Ari campaign rolls on, and has now picked up spectroscopy, UV (Galex), and X-ray (Swift - thanks Koji!) - to go along with the optical coverage. It has been mostly in a "zero-accretion-light" state for a few days, with some little spits here and there. There's an orbital hump in the light curve, yet the color is quite blue - so most likely it's hot WD + heated secondary. It's strange: we love CVs because of their disks, but when the disks go away, then we're *really* interested. joe From jop at astro.columbia.edu Wed Nov 18 04:19:08 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 18 Nov 2009 04:19:08 -0500 Subject: (cba:news) xss0056 again Message-ID: <4B03BC0C.8010706@astro.columbia.edu> and more usefully this time. The star's precise position is 00 55 20.0 +46 12 57 (J2000). It's also known as 1RXS J005528.0+461143 in the Rosat catalogue. Sorry - it's very late on the last night of an observing run. joe From jop at astro.columbia.edu Thu Nov 19 17:56:10 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 19 Nov 2009 17:56:10 -0500 Subject: (cba:news) TT Ari Swift observations Message-ID: <4B05CD0A.6090302@astro.columbia.edu> Here are expected UT times of X-ray observation on November 21. Mostly suited for Asian longitudes, where we have no coverage... but with some leakage to Europe and AU/NZ. Observations *near* these times have high value too! joe -------- Original Message -------- Subject: TT Ari - Swift schedule Date: Thu, 19 Nov 2009 11:13:23 -0500 From: Koji Mukai To: Joe Patterson Hi Joe, The first 6.5 ksec of the new Swift time has been scheduled for Nov 21. http://www.swift.psu.edu/operations/PPST/2009325/TTAri_ppt.html The expected UT times of observations are: 09:15-09:22 10:51-11:01 12:27-12:37 14:04-14:13 15:40-15:50 17:17-17:31 18:53-19:07 20:29-20:43 22:06-22:19 23:42-00:00 - Koji From jop at astro.columbia.edu Fri Nov 20 22:00:55 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 20 Nov 2009 22:00:55 -0500 Subject: (cba:news) More Swift TT Ari observations Message-ID: <4B0757E7.9010309@astro.columbia.edu> These are for the NEXT two nights. Basically Saturday and Sunday nights. Except for the first visit, there are no actual overlaps for observers in the Americas. Some overlap for AU/NZ, and lots for Europe and Asia. Unfortunately we still have no Asian observers in our network, but I hope that weather cooperates for some Europeans! We have good skies in the western US, so I guess it's too much to expect that the Lady Luck of satellite scheduling will smile on us as well. joe -------- Original Message -------- Subject: TT Ari Date: Fri, 20 Nov 2009 20:32:43 -0500 From: Koji Mukai To: Joe Patterson Hi Joe, Here are the current Swift schedule for TT Ari for Nov 22 & Nov 23. - Koji ---------- Nov 22: 8 visits, 8.3 ksec 01:18-01:26 11:19-11:39 12:58-13:16 14:34-14:52 16:10-16:29 17:47-18:05 19:23-19:41 20:59-21:18 Nov 23: 8 visits, 7.3 ksec 11:05-11:10 14:15-14:35 15:51-16:11 17:28-17:48 19:04-19:24 20:41-21:01 22:17-22:27 23:53-00:00 From jop at astro.columbia.edu Wed Nov 25 21:12:14 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 25 Nov 2009 21:12:14 -0500 Subject: (cba:news) [Fwd: CBET 2050: 20091126 : POSSIBLE NOVA IN ERIDANUS] Message-ID: <4B0DE3FE.5090702@astro.columbia.edu> Dear CBAers, With a galactic latitude of 31 degrees and a possible range of 8 mag, this could be an awfully interesting object. It could be a very nearby dwarf nova, or a really distant nova. Or maybe something else... but it's very much worth a looksee to figure out if the new object really is that 15th mag star. If it is, then I highly recommend a photometric run! And if not, well, it's still worth some study. joe -------- Original Message -------- Subject: CBET 2050: 20091126 : POSSIBLE NOVA IN ERIDANUS Date: Wed, 25 Nov 2009 20:52:31 -0500 From: IAUC mailing list To: iauc at libraries.cul.columbia.edu Electronic Telegram No. 2050 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS at CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT at CFA.HARVARD.EDU (science) URL http://www.cfa.harvard.edu/iau/cbat.html POSSIBLE NOVA IN ERIDANUS Hitoshi Yamaoka, Kyushu University, reports the discovery by K. Itagaki (Yamagata, Japan) of a possible nova (mag 8.1) caught on Nov. 25.536 UT with his 0.21-m patrol system. A confirming image taken by Itagaki on Nov. 25.545 with a 0.60-m reflector shows the object at R.A. = 4h47m54s.21, Decl. = -10d10'43".1 (equinox 2000.0). Itagaki notes that there is a faint (mag about 15) object near this position on his archival patrol images. Yamaoka suggests that it might be the brightening of a 15th-mag blue star that is contained in many catalogues (USNO-B1.0 position end figures 54s.19, 42".9), noting that the amplitude of seven magnitudes is rather large for a dwarf nova, but somewhat small for a rapid classical nova. Yamaoka adds that the ASAS-3 system (Pojmanski 2002, Acta. Astron. 52, 397) also detected this object at the following V magnitudes: Nov. 10.236 UT, [14.0:; 19.241, 7.34; 22.179, 7.98; 24.269, 8.12. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2009 CBAT 2009 November 26 (CBET 2050) Daniel W. E. Green _______________________________________________ iauc mailing list iauc at astro.columbia.edu https://mail.astro.columbia.edu/mailman/listinfo/iauc From jop at astro.columbia.edu Thu Nov 26 11:47:14 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 26 Nov 2009 11:47:14 -0500 Subject: (cba:news) Probable nova Eri 2009: the spectrum Message-ID: <4B0EB112.3050707@astro.columbia.edu> i haven't studied the spectrum yet, but this reported spectrum is much more suggestive of a nova, not a dwarf nova (the DN usually show just broad Balmer absorption, with some weak emission cores). Plus Tom Krajci's light curve from NM showed only weak variability at best. The star still has some serious 'splainin' to do; even as a nova, it's pretty odd, and possibly a good campaign target for us some day. Probably not now, though, unless new spectral evidence emerges, or rapid light variations. Maybe one of the southerners can be the Nova Eri sentry... joe -------- Original Message -------- Subject: [vsnet-alert 11694] Re: Bright eruptive object in Eridanus Date: Fri, 27 Nov 2009 00:55:49 +0900 From: Hiroyuki Maehara To: vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp, vsnet-campaign-nova at ooruri.kusastro.kyoto-u.ac.jp, vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp References: M. Fujii (Okayama, Japan) obtained a low-resolution spectrum of the object. He reports that the spectrum shows the Balmer (FWHM of H_alpha emission is 3200 km/s), He I (447.1, 501.6, 587.6, 667.8, 706.5 nm), N III (464.0 nm), Na I D (589.2 nm), O I(777.3, 844.6 nm), and Mg II (823.2 nm) emission lines. http://otobs.org/FBO/fko/nova/pn_eri_20091126.gif I also obtained a spectrum of the object which shows broad Balmer, He I, and N III emission lines. The FWHM of H_alpha emission is 3400km/s. http://www.kwasan.kyoto-u.ac.jp/~maehara/novae/ERInova2009_20091126.gif These features suggest that this object is a He/N nova. On Thu, Nov 26, 2009 at 02:21:57PM +0900, Taichi Kato wrote: > According to CBET 2050, Itagaki-san has discovered a bright (8.1 mag) > eruptive object in Eridanus (position 044754.21 -101043.1). > Although this object has been suggested to be a possible nova, > the object might also be a WZ Sge-type dwarf nova. > Spectroscopic and time-resolved photometric observations are urged. From jop at astro.columbia.edu Mon Nov 30 06:17:55 2009 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 30 Nov 2009 06:17:55 -0500 Subject: (cba:news) SDSS J012940.05+384210.4 outburst confirmed] Message-ID: <4B13A9E3.6080203@astro.columbia.edu> Dear CBAers, As we've come to suspect/learn over the last 15 years, the helium CVs have their own outbursts too, and with a morphology that might be very similar to their H-rich cousins. But these stars are so few in number that a star's first well-observed outburst is pretty big news - and an excellent reason to pounce! joe -------- Original Message -------- Subject: [vsnet-alert 11702] SDSS J012940.05+384210.4 outburst confirmed Date: Mon, 30 Nov 2009 20:06:02 +0900 From: Hiroyuki Maehara To: vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp, vsnet-campaign-dn at ooruri.kusastro.kyoto-u.ac.jp, vsnet-newvar at ooruri.kusastro.kyoto-u.ac.jp, vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp References: I confirmed an outburst of SDSS J012940.05+384210.4. Time-resolved observation is in progress. SDSSJ012940.05+384210.4 20091130.39918 150C Mhh.VSOLJ On Mon, Nov 30, 2009 at 10:38:40, Taichi Kato wrote: > According to Jeremy Shears (baavss-alert message), the suspected > AM CVn-type CV SDSS J012940.05+384210.4 may be undergoing an outburst. > The spectrum (Anderson et al. 2005 AJ 130, 2230) showed He I emission > lines (not very strong). Confirmatory observations and time-resolved > photometry is encouraged. > > === > > SDSS J012940.05+384210.4 Nov 29.045 14.5C > > Outburst needs confirming, please, as it was on a single BRT image which was not fully focused