From jop at astro.columbia.edu Sun Mar 12 08:32:12 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 12 Mar 2017 08:32:12 -0400 Subject: (cba:news) almost-pi-day cba-news Message-ID: in both pdf and .txt format joe p -------------- next part -------------- A non-text attachment was scrubbed... Name: stars312.pdf Type: application/pdf Size: 24585 bytes Desc: not available URL: -------------- next part -------------- March 12, 2017. Hi CBAers, Unless Christian or Enrique protests mightily, time to end the YZ Cnc campaign, or demote to once-a-week status. CN Ori is also at the end of the line. Time to quit. Nice result: all the previously published orbital periods appear to be wrong (in the third decimal place). The reason is subtle: in this ever-on-the-move star, the phasing of the orbital wave is not completely stable - it depends on brightness. Could this be a consequence of changes in disk size? A tempting interpretation... but one which awaits more careful analysis. We have long-term programs going om FS Aur and BY Cam. Many others too of course, but these are at the end of their observing seasons... and end-of- season runs are of special value because they help bridge the gap to the next observing season. So on some clear nights when you can get a long-ish run, have a go at these stars. This self-expires about April 1 (can't get blood from a turnip). Shawn Dvorak has started up the AM CVn season, and that's definitely a star for high-priority coverage over the next month. We need just one more high-quality timing to get a superb 24-year ephemeris. But each good- quality timing takes a week or more of coverage, because there are two stronger signals - the 1051 s and 1011 s superhumps - which have to be subtracted in order to isolate the 1028 s orbital signal. It's not that difficult to do this, but it does require a lot of concentrated runs - as long as you can go on it, and for a few weeks on end. I've written up our paper on the recurrent nova IM Nor. It appears to be a great match for T Pyx, which is mighty encouraging since T Pyx otherwise stands alone - no relatives! - in the CV zoo. But now that Norma season has rolled around again, I really want to get a few 2017 timings of the eclipse. It's 19th magnitude, so is probably a project for Gordon and Berto only (who have been able to get good data on it in the past). T Pyx. Now near the end of its observing season... and for the same reason cited above, a good time to get some long runs, to pin down the cycle count. Not that it's uncertain, but since the period is changing (mirabile dictu!), we have to keep vigilance on it. Berto has gotten one late-season run - another 3-5 will end its observing season nicely. NY Lup. Beginning of observing season for this DQ Her star. Beginnings are just as critical as endings, for the same reason. A few runs now would be great. Watch out for the contaminating neighbor star. Consider this list to be ADDITIVE to Enrique's list. He's more up-to-date than me concerning current targets, especially the DQ Her stars, which he tracks closely. I heartily concur in recommending EI UMa as a great northern target now. I've got the AAVSO/SAS June meeting on my travel schedule, and hope to see a bunch of you there! joe p -------------- next part -------------- ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Tue Mar 14 20:12:03 2017 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 14 Mar 2017 20:12:03 -0400 Subject: (cba:news) Fwd: [vsnet-alert 20780] Re: OV Boo outburst = SDSS J1507+52 In-Reply-To: <3ef7ab3c-5542-3e79-87e2-ff3b80dcf96e@kusastro.kyoto-u.ac.jp> References: <3ef7ab3c-5542-3e79-87e2-ff3b80dcf96e@kusastro.kyoto-u.ac.jp> Message-ID: <7bd9311d-c015-2d7b-7bd0-8f55a9e6f1bf@astro.columbia.edu> Hi CBAers, Yesterday in America, the CBO dominated the news. Today it seems to be the CBA - because one of our all-time favorite stars burst into its first known eruption. Bootis is decently available in the sky (1507+52)...so get thee to a telescope. At 12th magnitude you can even use a filter (V is best). But as usual, it's the time series we're most interested in, so a nice long time series in unfiltered light is just perfect. This could be a short outburst, so speed might be essential! joe -------- Forwarded Message -------- Subject: [vsnet-alert 20780] Re: OV Boo outburst Date: Wed, 15 Mar 2017 03:42:10 +0900 From: Keisuke Isogai To: vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp , vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp , baavss-alert-subscribe at yahoogroups.com, cvnet-outburst-subscribe at yahoogroups.com This is an additional information. OV Boo is also known as SDSS J1507+52. In order to explain why the orbital period is below the period minimum although the object has WZ Sge-like properties, Patterson et al. (2008) proposed that the secondary of OV Boo might be a Population II (metal-poor) star. (Because Pop. II star is smaller than normal stars.) However, the spectroscopic study is insufficient, and the population has not been confrimed. If this outburst is "metal-poor outburst", the behavior might be different from the ordinary DNe outburst. On 2017?03?15? 02:51, Keisuke Isogai wrote: > OV Boo has ultra-short period of 0.046 d, and the period is below the period minimum. > By the spectroscopic study, Patterson et al. (2008) suggested that OV Boo is a member > of WZ Sge stars, but the object had shown no outbursts. > This outburst is very likely to be a WZ Sge-like superoutburst. Thus time-series > observations are strongly encouraged. > > On 2017?03?15? 01:42, Seiichi Yoshida wrote: >> Dear colleagues, >> >> I am Seiichi Yoshida working on the MISAO Project. >> >> Masaru Mukai, Kagoshima, Japan, reported that OV Boo >> (R.A. 15 07 22.35, Decl. +52 30 39.8) is bright as 11.4 mag on >> Mar. 14.63 (UT), using Nikon 105-mm lens + CCD (STL6303E) + IR-cut >> filter. >> >> The VSX data shows it is a CV+EA+ZZ/GWLIB type with a range of >> 18.0-20.6 mag. >> Best regards, >> >> -- >> Seiichi Yoshida >> comet at aerith.net >> http://www.aerith.net/ >> > ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists http://cbastro.org/communications/mailing-lists/