From jop at astro.columbia.edu Wed Apr 4 12:59:59 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 04 Apr 2012 12:59:59 -0400 Subject: (cba:news) bk lyn supermax Message-ID: <4F7C7E0F.2090905@astro.columbia.edu> HI CBAers, Data from Joe Ulowetz and Richard Sabo show that BK Lyn has now jumped into supermax. A very fine target now in general, and especially with Olde Whiteface lurking up there. DI UMa and RZ LMi are definitely birds of a feather - more challenging targets usually, but will very likely reward your faithful attention. Decent coverage so far on RZ LMi, but DI UMa has been somewhat neglected. Unfairly, I'd say. It's April, and that definitely means time to fire up the AM CVn campaign. This star never entertains much - pretty flat light curve! - but usually flashes a beautiful set of periodic signals. Low amplitude, but stable. Good target for the smaller scopes, and for relatively cloudy nights. joe From jop at astro.columbia.edu Thu Apr 5 10:28:58 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 05 Apr 2012 10:28:58 -0400 Subject: (cba:news) bk lyn in full glory Message-ID: <4F7DAC2A.30003@astro.columbia.edu> Joe Ulowetz's data last night showed BK Lyn at a bright supermax, V=13.7. And this "clear" magnitude usually underrates the actual V brightness by about 0.2 mag. Lynx is not an ideal location on April nights... but BK Lyn sure is an ideal target! Also, we don't have all that much data in the brightest phases of a supermax. It's true I'm getting greedy; we already have ~950 hours of coverage this year. But I promise never to be greedy again. Ever. Fire up those telescopes in the days/weeks to come! joe p From jop at astro.columbia.edu Fri Apr 20 06:53:18 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 20 Apr 2012 06:53:18 -0400 Subject: (cba:news) targets for mid-April Message-ID: <4F91401E.9080800@astro.columbia.edu> Dear CBAers, I hope/expect to see you a bunch of you (I think ~10-12) at the Big Bear/AAVSO meeting. As usual, we'll have a few meals together and perhaps meet once to discuss common issues. Enrique and I have been scrambling to get our papers submitted (basically on ER UMa and BK Lyn)... and I haven't managed to dig up all the authors' addresses. (Since it's a 20-year campaign, it's not that easy.) In a few days I'll send the submitted version to authors. Partly because the time-series data is so rich, I've decided to postpone the detailed analysis and highlight the glamor points (only short-period novalike, only novalike to morph into a dwarf nova, oldest recovered nova). The long-term campaigns are all going well. The Sun's relentless eastward march has reduced ER UMa and BK Lyn to evening-only status, but they're still good targets for another few weeks. The other really long-term campaign targets, CR Boo and V803 Cen, deserve a continued high priority. In a few days I'll have 'em analyzed enough to give a report. Then there's AM CVn. It's *definitely* time to get some long runs on that star. MANY long runs. This is definitely the month, when it transits near midnight and the nights are still decently long. Since it's always near 14.2, it's bright enough for everyone and at all tmes (even the Moon stays away from Can Ven). I had thought we had a secure orbital-period decrease through 1992-2010, but made the mistake of wanting to confirm with 2011 data. Great was my chagrin when I saw the 2011 timings of orbital minimum occurring 0.10 cycles late. Was this just a fluke, to be quickly overcome by the 2012 timings? Or was I just too quick on the draw before that? This coming season should determine... and will constrain the angular-momentum loss rate of the binary. Finally, and potentially a real gem, there's the bright Seyfert nucleus of MCG-6-30-15. Encarni Romero Colmenero is about to start a long spectroscopic monitoring campaign ("reverberation mapping") from SALT, and needs daily V magnitudes for a couple months, starting now. She'll write to this address and specify details... but it looks like a really good fit for us. At a dec of -34, I assume this is strictly a southern object, though some of you borealites might be feeling adventurous. Anyway, read up on this fascinating galaxy and its central object, make a chart, find a comp star, and measure a few magnitudes - through V, or Sloan g, or unfiltered. Try to figure out how you would observe - which filter, how to cope with galaxy background, etc. Measure *vastly* more more than one magnitude per night; that will improve knowledge of errors, and help define the true, unknown timescales of variability. I'm sure Encarni will send information on these matters. joe From jop at astro.columbia.edu Sat Apr 21 06:55:38 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 21 Apr 2012 06:55:38 -0400 Subject: (cba:news) CR Boo superoutburst Message-ID: <4F92922A.3090008@astro.columbia.edu> Dear CBAers, The last day's observations from Tut and Enrique show that CR Boo has jumped into superoutburst. The major part of CR Boo's supers is always brief, and we've never caught one really well. Therefore, we've never obtained the precise information we're used to getting from superoutbursts in general. The equatorial location hurts us too - either because runs are short, or perhaps because people decide not to observe it (horizon, expected short duration, etc.). Anyway, the timing is perfect now, and it would be great to follow this elusive star tree to tree. Enrique's comparison star is the AAVSO 137 star, with V=13.733. Spookily, that's the exact frequency of BK Lyn's negative superhump in c/d. Hint to lottery players? joe From jop at astro.columbia.edu Tue Apr 24 12:43:07 2012 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 24 Apr 2012 12:43:07 -0400 Subject: (cba:news) Fwd: (cba:chat) SBSS 1108+574, ultrashort CV? In-Reply-To: <78E52B75-4CB5-4EAE-BF98-DE826A05C836@gmail.com> References: <78E52B75-4CB5-4EAE-BF98-DE826A05C836@gmail.com> Message-ID: <4F96D81B.5020504@astro.columbia.edu> I imagine you all got this, but just wanted to stress its importance. This 55 minute period is in sort of a forbidden zone - too short to be an SU UMa, too long for an AM CVn. Let's bear down and learn what we can from this rare outburst. At least I assume rare... after all, it's the first one seen. joe Hi all, There was a vsnet alert 2 days ago regarding an outburst detection by CRTS of SBSS 1108+574 (11:11:26.80 +57:12:38.7). A new alert yesterday suggested a short period for this target. I'm still running, but after ~5.5 hours, it's superhumping (amplitude ~0.20 mag) at mean mag ~15.8, and period below 1 hour (0.931 h). This is a very blue object, with SDSS color g-r=-0.03. Probably an ultrashort period CV of who knows what type ...... Enrique ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/