From jop at astro.columbia.edu Wed Mar 1 16:44:27 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 1 Mar 2000 16:44:27 -0500 (EST) Subject: (cba:news) U Gem erupting Message-ID: Dear CBAers, Well, U Gem is finally erupting, and I hope you can get to it soon , especially during eclipse phases (although coverage at all times will be useful). This coincides with coverage of two other erupting dwarf novae, SW UMa and OY Car. All are important, and I hesitate to rank them - except to say that the best practice is to keep to one. The best science usually comes out from repeated measurements of a single object. At +22 degrees dec, U Gem is presumably available to the Aussies and Kiwis. Don't be bashful, just cuz Gemini is not exactly your home turf! joe From jop at astro.columbia.edu Sat Mar 18 12:49:00 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 18 Mar 2000 12:49:00 -0500 (EST) Subject: (cba:news) Arise, ye of the nether regions Message-ID: and behold the very bright outburst of V803 Cen reported by Andrew Pearce and Rod Stubbings yesterday. This is what we've been waiting for, a probable - well, excellent candidate anyway - superoutburst. We've only gotten fragmentary coverage of the bright stages of superoutbursts, as you can see from the in-press paper on the website. You need to move fast, as this star has much briefer supers than is the norm for the H-rich SU UMas. The aftermath of the super is also worth close study. In the paper we merely speculated about the sequence of events, based on fragments spliced together over 7 years. Now we get to find out, with your help, what fraction of our speculations is actually true! OY Car has finally sunk into the grass, it gave us all some good times but it's time to move on. Long live V803! For borealites, DW UMa is the choice star right now if you can tolerate that ol' devil Moon. If you can't, then AC Cancri or CR Boo. (CR Boo is good for southerners too, but V803 is much more important right now!) joe From jop at astro.columbia.edu Tue Mar 21 12:05:01 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 21 Mar 2000 12:05:01 -0500 (EST) Subject: (cba:news) v405 Aur and v803 cen mainly Message-ID: Dear CBAers, I just wanted to add my voice to Coel's urging observation of V405 Aur = RXJ0558+5353 over the next few days - to coincide with an HST observation. Not the greatest time for Auriga, nor the greatest weather (Eastern and Southwestern US presently stormy), but simultaneity with HST is precious indeed! And for australites, I note with glee that V803 Cen is remaining bright. I only hope that you've been out there pushing back the frontiers of knowledge! joe From jop at astro.columbia.edu Mon Mar 27 07:29:51 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 27 Mar 2000 07:29:51 -0500 (EST) Subject: (cba:news) oy car, and aas meeting Message-ID: Dear CBAers, Mostly southern talk first. I've studied the V803 Cen data sent in so far, and concur with Stan: the star is now in its cycling state, with a period that is perhaps slightly shorter than in 1997 (20 hr versus 23 hr). This far off resonance with the 24-hour cycle of our home planet, there's a tendency to see "outbursts" where the reality is just little maxima of a rapid cycle. This describes data furnished by Robert Rea, Maria Marsh, Fred Velthius, and Jennie McCormick, during JD 625-629. But it's likely (not absolutely certain) that the earlier rise was V803 Cen's version of a superoutburst - a pretty quick affair (3-4 days long) with no important cycling within it. Stan, do you agree with this? (I haven't seen your data yet, and they may well establish or refute this). Small 1610 s superhumps punctuated that 625-629 data, but I was hoping for the big humps that we saw only once - in 1992. They woulda been slightly earlier. Any coverage slightly earlier? The possibly shorter period is definitely of interest now, so it's a good target for continued coverage. OY Car is back at minimum now, but I've studied the data closely and it supplies a wonderful record of superhump and eclipse changes in a dwarf nova. It shows by far the clearest sign of an elliptical disk, in the oscillation of the time of mid-eclipse. I'm writing it up now for publication. Since most of the contributing observers are somewhat new to our network, I'd like to include some detail about each person's telescope, observatory, observing procedure, detector, and data analysis procedure. And about the people too, though that part probably won't get through the editor into the scientific paper. Can you send me such stuff forthwith? Some of this I'd like to exhibit at the AAS meeting in Rochester on June 5. I hadn't realized this till an hour ago, but there will evidently be a day on (nominally) professional-amateur collaboration in astronomy. I'll certainly be there, and I hope to convince some of you to come too. There will I believe be a minor-planet (you know, the killer variety) conference at or near Alfred University just afterwards, which John Stull and Gordon Garradd must know all about. John or Gordon, could you let us know? In the north, DW UMa remains the best target. In the south, v803 Cen and BR Lupi. The latter is kind of a fishing expedition, but I know from my correspondence that some of you like fishing. And so do I. joe From jop at astro.columbia.edu Fri Mar 31 10:27:25 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 31 Mar 2000 10:27:25 -0500 (EST) Subject: (cba:news) CR Boo and UMa transient Message-ID: <200003311527.KAA02053@tristram.phys.columbia.edu> 3/31/00 Dear CBAers, We're enjoying a fine early spring in the Northeast - just about average for clear nights, but great for golf and baseball. Much treasured by those of us living in concrete jungles! We got pretty good response on DW UMa - from Dave East, Cap'n Bob, and Brian Martin. But the star disappointed - no big superhumps like it showed in 1996 and 1997. Time for us borealites to move on. Then a couple of days Ron Remillard announced a new X-ray transient in UMa (where there sure are a lotta fireworks this year), and optical ID from Uemura and Buczynski has pinpointed the position: 11h 18m 10.79s, +48d 02m 11.2s (2000.0). It appears to be about 13th magnitude. Let's get cracking on this guy, it's definitely the object of choice for northern telescopes now. Until the UMa transient, I wanted to kick off the 2000 all-site campaign on CR Bootis, which at 1346+08 is well-placed for everyone now. John Thorstensen will obtain spectroscopy in a week's time, so I wanted to start the photometric campaign now, and go for about six weeks. We did a fair job on CR Boo in 1996, but that was before we established a strong node in NZ. Now we can do much better in terms of global coverage, which is essential here because the putative dwarf-nova cycle is about 18 hours. Then the UMa transient came along. Here's a compromise: could the southern observers start the campaign now, and we in the north will do CR Boo as a secondary target? That way we'll get some global coverage now, to be simultaneous with spectroscopy, and will switch to all-site coverage when the bloom is off the UMa rose. I have to admit, it might be a little dangerous to switch off V803 Cen so soon. But as Stan (and Andrew Pearce) recently remarked, it seems to be doing its up-and-down cycling thing - and we've already documented that pretty well. We know a lot less about CR Boo, and we could know a lot more, since it's accessible to all of us. Fred Velthius and Jennie McCormick sent some nice data on VZ Pyx, which I haven't yet been able to study thoroughly. I did study the amazing Kiwi data on OY Car, which form one of the finest records of a dwarf-nova outburst I have ever seen! I'll send some of that as soon as I get out of class this afternoon. UMa transient and CR Boo - pretty simple this time! Joe