From jop at astro.columbia.edu Fri Aug 1 18:16:19 2008 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 01 Aug 2008 18:16:19 -0400 Subject: (cba:news) stars for august Message-ID: <48938B33.5050407@astro.columbia.edu> Dear CBAers, Back from another trip - thanks for your patience, and I'll now get down to CBA biz! The major targets of July are mostly due for retirement. VY Aqr is still flopping around with "echo outbursts" and exhibiting some superhump activity. It's still a decent target, but harder now because the humps are getting tough to track. So I'm kind of middling about it. It's no longer possible to get really long runs on GW Lib, so that one also deserves semi-retirement. Jerry Foote has found powerful superhumps at 2.5 hrs from MN Dra, and it's definitely time to launch a strong campaign on this interesting northern "period-gap" star. Our previous efforts kind of fizzled, but Jerry's humps look we'll got some very fine results from it. Act fast! We've hardly ever observed, so just pick out a good comparison star and let 'er rip. Two other good northern targets are worth highlighting. One is WZ Sge. We've never done a long campaign at quiescence, and it's now perfectly placed. Let's start it up! Examine the images carefully, though - there's a contaminating star about 11 arcsec away, so poor seeing or drive issues might make this target unfeasible. Decently bright at 15.2. The other is SDSS2333+15 (Peg). This shows several periods in the tens-of-minutes range, so it's a perfect target for our network which can disentangle periods very well. And if you need a brighter target, I recommend AO Psc; it's at mag 13.4 and a (nicely matched) 14.3 min period. At 2254-03, it's good for all hemispheres. A good target for australites is BW Scl; I'm about to finish our multi-year study of it, and a final season of coverage would be great. More in a few days. Now that I'm back in New York to stay, I can catch up on all the personal correspondence I've neglected... joe From jop at astro.columbia.edu Tue Aug 5 23:56:57 2008 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 05 Aug 2008 23:56:57 -0400 Subject: (cba:news) outbursting dwarf novae Message-ID: <48992109.50609@astro.columbia.edu> Dear CBAers, The dwarf novae have been a little quiet in our sky lately. But there are three freshly erupted which are likely to be good targets. HO Del has had very little activity in the last decade, and has just erupted to what is very likely a full superoutburst. Perfectly placed (transiting near local midnight), it's a GREAT target for borealites, and quite possibly OK for some of the australites too (at +14 degrees). Fire away! The two fully southern DN are more speculative. V893 Sco is a bright eclipser, and we would love to find superhumps in it - and sort of expect them. But they've never been found, despite the very favorable Porb. Very odd. Bright now at 12.7. RU Hor is a very sparsely observed SU UMa star, and really needs a substantial observing campaign to nail down its credentials. Bright now at 14.0 - time for action! Best to take one of these and fire away for time series as long and as sustained as possible. That's almost always a very good observing strategy - and I think it is here. joe From jop at astro.columbia.edu Thu Aug 7 08:44:13 2008 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 07 Aug 2008 08:44:13 -0400 Subject: (cba:news) RU Hor superhumps Message-ID: <489AEE1D.9040703@astro.columbia.edu> DEar CBAers, Bob Rea's first night on RU Hor showed powerful superhumps with a period near 0.071 d... so that's an affirmatory - great target for southern observers in these brisk August morning skies! joe From jop at astro.columbia.edu Sun Aug 10 09:48:03 2008 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 10 Aug 2008 09:48:03 -0400 Subject: (cba:news) DN outburst in Taurus Message-ID: <489EF193.3000609@astro.columbia.edu> Dear CBaers, Not the best sky position... but plenty worth following - DN of very short period are potentially very sinificant targets! joe -------- Original Message -------- Subject: CBET 1463: 20080809 : CATACLYSMIC VARIABLE STAR IN TAURUS Date: Sat, 9 Aug 2008 10:42:35 -0400 (EDT) From: IAUC mailing list To: iauc at libraries.cul.columbia.edu Electronic Telegram No. 1463 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 CATACLYSMIC VARIABLE STAR IN TAURUS H. Yamaoka, Kyushu University, reports the discovery by K. Itagaki (Yamagata, Japan) of a variable star (mag 14.1) on an unfiltered (red) survey CCD image taken with a 0.21-m f/3 reflector (with confirming images taken with a 0.60-m f/5.7 reflector) around Aug. 7.7 UT. The variable is located at R.A. = 4h06m59s.78, Decl.= +0d52'44".3 (equinox 2000.0), and it was fainter than mag 17.0 on Itagaki's survey image taken on 2007 Oct. 13. H. Kaneda (Sapporo, Japan) notes that an x-ray source (1RXS J040700.2+005247) is located within 7" of the reported position, and the variable should be identical with a USNO-B1.0 catalogued star (B1 mag 18.4, R1 mag 17.5) whose position end figures are 59s.82, 44".3. Yamaoka adds that the NOMAD catalogue shows that the variable was caught in a bright state in the YB6 catalogue (USNO, unpublished, epoch unknown) at B = 14.3 and V = 14.35. Following posting on the CBAT's unconfirmed-objects webpage, C. Jacques and E. Pimentel (Belo Horizonte, Brazil) write that they obtained a 60-s unfiltered CCD image on Aug. 9.46 remotely using a 0.25-m f/3.4 reflector near Mayhill, NM, U.S.A., finding position end figures 59s.82, 44".0 and mag 13.7. Yamaoka adds that H. Maehara (Kyoto University) has found that the variable was detected via ASAS at V = 13.5 on Aug. 4.42 but was fainter than the detection limit on July 25.41, with other outbursts (V = 13.5-14) occurring on 2004 Oct. 20 and 2006 Mar. 16. Maehara adds that photometry by G. Bolt on Aug. 8 show the variable to display clear superhumps with an amplitude of 0.2 mag and period around 0.06 day, which indicate that the object is an SU UMa-type dwarf nova. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2008 CBAT 2008 August 9 (CBET 1463) Daniel W. E. Green _______________________________________________ iauc mailing list iauc at astro.columbia.edu https://mail.astro.columbia.edu/mailman/listinfo/iauc