From jop at astro.columbia.edu Wed Oct 18 08:34:01 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 18 Oct 2006 08:34:01 -0400 Subject: (cba:news) Stars for October Message-ID: Dear CBAers, Time to replace the menu of stars, as the Sun rolls eastward. EF Tuc has received good coverage, mainly from Berto and David Moorhouse. It looks like a tough nut to crack - there's a good candidate period near 3.5 hours, but this doesn't agree with well with last year's (indecisive) result. Some more analysis is needed here, so for now - and probably for the year - we should sweep EF Tuc off the table. The main northern star of the month has been IGR0022+61 = "Cas". And a damn interesting one too. Lots of coverage from Bart Staels, Tom, Bob Koff, and Dave Messier. Beautiful 9 minute period in this star, with a whopping 0.2 mag amplitude! Almost certainly this signifies the white- dwarf rotation, with the orbital period still not specified. With ~40 runs so far this year and sufficient period constraint to count cycles back to last year, it's time to quit. Some more work on the analysis, and/or a little spectroscopy, is very likely to yield Porb too. (The early odds favor 2.7 hours.) I propose replacing these S/N principal targets with two others: BW Scl and HS2331+39 = "And". We've been getting occasional coverage of each... mainly from Bob Rea and Lew Cook. Now it's time to kick the campaigns to a higher gear, and observe 'em pretty intensively during the present dark run. Both are bellwether stars for the theory of late evolution of CVs. And both somewhat challenging around mag 16.5 or so. An easier northern target is V709 Cas, at mag 15.0. Despite its very favorable sky location, we've not had a lot of success with campaigns on this star - it usually gets squeezed out by other priorities. The star has a fast period (313 s), and it would be great to time that signal over the course of the next month or so. You have to make sure your cycle time (integration plus readout) is less than 90 s, and preferably less then 60 s. AO Psc is a similar story, only here the star is essentially equatorial (2254-03), and the star is a more relaxing V=13.6, P=858 s. AO Psc is a star you can truly grow to love! Finally I wanted to proffer a couple of odd stars which we have never observed, and have hardly been observed by anyone. These are "Cep" = HS0229+80 and "Oct" = LB9963 = 0250-87. Obviously bookended near the celestial poles, which in part explains why they're unlikely targets of equatorial telescopes. Both about 14th mag, and both likely, but not certain, to be CVs. I dunno what they are - but you might be able to find out. If you're trying to figure out how to observe stars in such an awkward place, consider the possibility of mis-aligning your telescope - it'll cause some other havoc but might get the job done. By the way I rolled the dice and got married (second time) two weeks ago. Beautiful fall day in Central Park, very memorable. I even wrote some poetry for it and there was even astronomy - though nothing about variable stars - in it. Not as extreme as the first time, though, when I got strangely fascinated by neutrinos while writing the ceremony. Maybe that was an omen for a marriage with very low cross-section. Happy observing! Joe From jop at astro.columbia.edu Tue Oct 24 13:51:25 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 24 Oct 2006 13:51:25 -0400 Subject: (cba:news) SS LMi, a long-shot target... Message-ID: <453E529D.9050201@astro.columbia.edu> Dear CBAers, I noticed Jeremy Shears' announcement of SS LMi in outburst - this is sort of a mystery object, and from his description of a 90-minute light curve, it sounds like a good candidate as a superhumping DN. The sky position is really quite bad, but I think if we can patch together some time series in Europe and the USA, we can learn the period (and assess the nature of the variability). Tempting target for that last 2 hours of the night! Also, I should remove HS0229+80 from our list of stars; I've seen a few nights now, and the variability is quite weak... not really in our realm of interest unless the star does something else to boost its priority. joe -------- Original Message -------- Subject: [cvnet-discussion] SS LMi: time resolved photometry Date: Tue, 24 Oct 2006 09:32:25 +0000 From: Jeremy Shears Reply-To: cvnet-discussion at yahoogroups.com To: baavss-alert at yahoogroups.com , CVnet-discussion , cvnet-outburst at yahoogroups.com I carried out unfiltered photometry on this object for 90 mins from Oct 24.177 this morning, i.e. until dawn. During this time the object declined from 16.2C to 16.5C, then gradually rose again to 16.1C. Follow-up photometry is strongly encouraged. Given the doubt about the identity of this object in the past, I have uploaded an image to the Files section of CVnet-discussion. Best regards, Jeremy Shears Cheshire, UK _________________________________________________________________ Be one of the first to try Windows Live Mail. http://ideas.live.com/programpage.aspx?versionId=5d21c51a-b161-4314-9b0e-4911fb2b2e6d Visit us on the web at http://cvnet.aavso.org Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/cvnet-discussion/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/cvnet-discussion/join (Yahoo! ID required) <*> To change settings via email: mailto:cvnet-discussion-digest at yahoogroups.com mailto:cvnet-discussion-fullfeatured at yahoogroups.com <*> To unsubscribe from this group, send an email to: cvnet-discussion-unsubscribe at yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/ From jop at astro.columbia.edu Fri Oct 27 14:13:13 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 27 Oct 2006 14:13:13 -0400 (EDT) Subject: (cba:news) RE: New Object In Tau..... appears to be a UGSU-type CV (fwd) Message-ID: Dear CBAers, Zowie, it looks like two of these new objects (SS LMi and the new object in Tau) are reporting in with superhumps of very short period (75-80 min or so). This is quite fertile territory... and most such stars, at least the ones freshly discovered, turn out to be quite rare outbursters. Really great targets for October nights! joe ---------- Forwarded message ---------- Date: Thu, 26 Oct 2006 22:07:55 -0600 From: Tom Krajci Reply-To: cba-chat at cbastro.org To: cba-chat at cbastro.org, aavso-photometry at mira.aavso.org, BAAVSS alert , CVnet outburst , cba-news Cc: David Boyd Subject: (cba:news) RE: New Object In Tau..... appears to be a UGSU-type CV I started an imaging run on this object at 04:00UT 27 Oct. Conditions are clear but very windy. However I think I can get reasonably good data if the wind does not increase (forecast is for winds to lessen slightly). ------------------------------------------- Tom Krajci Cloudcroft, New Mexico http://overton2.tamu.edu/aset/krajci/ Center for Backyard Astrophysics (CBA) https://cbastro.org CBA New Mexico American Association of Variable Star Observers (AAVSO): KTC http://www.aavso.org/ ------------------------------------------- -----Original Message----- From: cba-news-bounces at cbastro.org [mailto:cba-news-bounces at cbastro.org]On Behalf Of David Boyd Sent: Thursday, 2006-October-26 19:39 To: aavso-photometry at mira.aavso.org; BAAVSS alert; CVnet outburst; cba-news Subject: (cba:news) New Object In Tau..... appears to be a UGSU-type CV 4 hrs of V and I-band CCD photometry of this new object, reported earlier by astronomers at Crni Vrh Observatory of the University of Ljubljana, shows a strong superhump signal with peak-to-peak amplitude 0.2 mag around a mean V mag of 15.10 indicating it is probably a UGSU-type CV. The V-I colour index is very close to zero. The mean superhump period over this 4 hr interval is 0.0541 +/- 0.0027d, using Peranso. These measurements used USNO-B1 1028-0043851 as a comparison, thanks to Wolfgang Renz for circulating this information. Equipment was 0.35m SCT with SXV-H9 CCD. Position measured as RA 03 29 12.26 +/- 0.19 Dec +12 50 17.54 +/- 0.12 (2000) using Astrometrica and UCAC2. Further time-series observations are encouraged. Regards, David Boyd (BDG), West Challow, UK -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.408 / Virus Database: 268.13.13/500 - Release Date: 2006-10-26 ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri Oct 27 14:55:04 2006 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 27 Oct 2006 14:55:04 -0400 (EDT) Subject: (cba:news) VARIABLE STAR IN TAURUS (fwd) Message-ID: and this is the formal announcement... ---------- Forwarded message ---------- Date: Fri, 27 Oct 2006 14:43:09 -0400 (EDT) From: IAUC mailing list To: iauc at libraries.cul.columbia.edu Subject: CBET 701: 20061027 : VARIABLE STAR IN TAURUS Electronic Telegram No. 701 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://cfa-www.harvard.edu/iau/cbat.html VARIABLE STAR IN TAURUS J. Skvarc, Crni Vrh Observatory, reports the discovery of a new star-like object (mag about 15.2) on four unfiltered CCD images (limiting mag 18.5) taken during Oct. 26.010-26.037 UT in the course of the PIKA project at with the Crni Vrh 0.60-m f/3.3 Cichocki telescope. The new object is located at R.A. = 3h29m12s.26, Decl. = +12d50'17".6 (equinox 2000.0 presumed); nothing is visible at this location on Crni Vrh archival images taken on 2004 Sept. 10, Nov. 16, and 2005 Jan. 22 (limiting mag 18.5) or on several Palomar Sky Survey and 2MASS images from the Aladin database. Confirming unfiltered CCD images were taken with a 0.40-m f/3.6 telescope by R. Palcic at Rezman Observatory (Slovenia) during Oct. 26.905-26.909 showing the object at similar brightness. Following a request by E. O. Waagen to AAVSO members, several observers have sent their confirming observations. R. Miles, Stourton Caundle, Dorset, England, reports the following position end figures for the variable star (at V = 15.2-15.3) from unfiltered CCD images taken on Oct. 26.963 with a 0.28-m f/10 Schmidt-Cassegrain reflector: 12s.24 +/- 0s.01, 17".6 +/- 0".1. D. Boyd, West Challow, U.K., reports that his V-band CCD exposures with a 0.35-m Schmidt-Cassegrain reflector, presumably taken around Oct. 27.0 UT, yield V = 15.2, V-I about 0, and position end figures 12s.26 +/- 0s.19, 17".5 +/- 0".1; he adds that 4 hr of V- and I-band photometry shows a strong superhump signal with peak-to-peak amplitude 0.2 mag, indicating that it is probably a SU UMa-type cataclysmic variable. The mean superhump period over this 4-hr interval was 0.0541 +/- 0.0027 days. R. Stanton, Three Rivers, CA, reports unfiltered CCD mag approximately 15.4 on Oct. 27.25. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 October 27 (CBET 701) Daniel W. E. Green _______________________________________________ iauc mailing list iauc at astro.columbia.edu https://mail.astro.columbia.edu/mailman/listinfo/iauc