From jop at astro.columbia.edu Wed Aug 2 17:15:11 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 2 Aug 2000 17:15:11 -0400 (EDT) Subject: (cba:news) Stars for August Message-ID: Dear CBAers, Haven't seen the Sun in a very long time, but I hope the weather is fine where you are. Here's the update on our various campaigns... Lew Cook and Bob Fried have continued to visit V1494 Aql episodically, and the star is continuing to fade as expected. It's now about 0.4 mag fainter than during our last strong campaign. In view of its continued excellent sky position, I'd say it was timely to resume close coverage. I'm especially hoping for strong contribution from NZ and Europe, to flog the noise down ever more vigorously. The other good star for campaigning now is V751 Cyg; so far it has been an all-USA affair, give us some company. The superhump of last year appears to be hanging in there quite well. And lastly the DQ Hers, all nice targets. AO Psc has been particularly abandoned this year, I'm about to call CV Welfare Services. No dwarf novae heating up the news-wires (unless some of you have decided to pounce on DH Aql, which would be nice) right now, but we're always alert to the most interesting. joe From jop at astro.columbia.edu Wed Aug 2 17:31:55 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 2 Aug 2000 17:31:55 -0400 (EDT) Subject: (cba:news) V803 Cen - borealites ignore Message-ID: Oops, Stan just emailed me that V803 Cen may be starting a superoutburst. It is way, WAY late for a real campaign in Centaurus, but there is a nagging doubt in my mind about this star that has always prevented me from fully (well, absolutely fully) embracing the view that it's "just a dwarf nova". All other SU UMas make their superhumps very rapidly and with very high amplitude (0.2-0.3 mag) at or near the beginning of superoutburst. Our 1992 coverage suggested this was the case, but certainly did not prove it; so far, the arguments supporting this allegation that I stitched together for this year's paper were based on data segments from *different* superoutburst (and even post-superoutburst) episodes. That's just too uncertain to be unreliable. All we need to do is follow the star for an hour per night for 5 nights. That'll test the hypothesis. If the hump amplitude drops sharply, we can happily yawn and throw V803 Cen into the dwarf-nova bin. Pretty nice reward for a little work! joe From jop at astro.columbia.edu Fri Aug 25 06:55:06 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 25 Aug 2000 06:55:06 -0400 (EDT) Subject: (cba:news) Stars of Aug-Sep 2000 Message-ID: Dear CBAers, I'm finally back from many travels of summer 2000. Here's some news of target stars. The DV UMa paper is scheduled for the December 2000 issue of PASP. It seems likely that IY UMa = Takamizawa will appear in the same issue (possibly the next). The paper on V751 Cygni (primarily 1999 data, some 1993 and 2000) will be submitted next week - it was a classic negative superhumper, and we found all the relevant periods (P-orb, P-sh, and the beat period which we identify as the wobble period of a tilted accretion disk). So much for northern stars. We're ending the V751 Cyg campaign now, mission accomplished. The campaign on V1494 Aql is going very well, with lots of work from NZ keeping aliases under great control. But the star's waveform appears to be stable, so I'm inclined to let it relax some more from its 1999 classical nova eruption, and revisit it again NEXT YEAR. So those are the two major campaigns going now - let's end 'em both. The main star I want to promote now is V1315 Aql. I think there's about a month left in the Aquila observing season, and if we can get Europe-North America-Australasia coverage, we can solve the outstanding quiestion. In the last campaign we got a nice superhump period, but cycle count ambiguity made it uncertain whether it was positive or negative (the peaks in the power spectrum were even-steven). This can be resolved in 2 weeks of vigorous campaigning. And after that it'll be time for another campaign on UU Aquarii! Decently equatorial and bright stars for family fun. I see that charts aren't yet up on the CBA site (Jonathan, any chance?), but they're in Downes and Shara (Feb 1993 PASP) and their coords are: V1315 Aql = KPD 1911+1212 19 13 54.6 +12 18 2.3 decent looking comps to the SW and NW UU Aqr 22 09 5.8 -3 46 18.5 the close companion immediately to the south (and slightly W) looks best Finally the V803 Cen story is worth some exultation. For 3.5 years I've been working to measure Porb and Psh in this helium star. We've had some good campaigns but could just not get a precise measure. I chalked it up to bad luck - that this star, unlike all the others, just has too sloppy a clock and hence resists efforts to nail down the period. That may be true to some extent, but the May 2000 campaign (data from Fred Velthius, Jennie McCormick, Robert Rea, Maria Marsh, Brian Warner, Claire Backman, and in the pipeline from Stan Walker) has clarified the matter. The superhump period is very close to Porb - just 0.4% longer. This indicates a very, very low mass secondary - about 0.017+-0.005 Mo. This is "the oldest known CV", where the secondary has been whittled down to practically nothing (the pure helium content indicates that the whittling has long ago reached the stellar core). What a wonderful star mister Centauri has turned out to be! Oh yes, there is also a far northern star I'd like borealites to start watching. This is GD 552, or "Cep 1" in the Downes and Shara catalog. It's about 16.5, basically a dark-sky target, but virtually nothing - make that nothing - is known about its photometric activity on long (eruption) and short (nightly) timescales. It's my other candidate "substellar" secondary in the CV zoo. It's better suited to Oct-Nov coverage, but who knows when the star might erupt and/or shake some periods at us. So - prime target V1315 Aql. Happy non-trails... (background lilt of cowboy music) to you, da-dah, da-dah, da,dah. joe From jop at astro.columbia.edu Wed Aug 30 17:27:12 2000 From: jop at astro.columbia.edu (Joe Patterson) Date: Wed, 30 Aug 2000 17:27:12 -0400 (EDT) Subject: (cba:news) V405 Vul - superhumps have (fully) grown (fwd) Message-ID: Dear CBAers, This star sounds like a wonderful new discovery - let's fire away at it! 2000 coords 19 53 05.0 +21 14 50 Go for it - a good project until the star sinks down into sky noise. joe ---------- Forwarded message ---------- Date: Wed, 30 Aug 2000 20:57:33 -0000 From: Tonny Vanmunster To: vsnet-alert , Vsnet-Campaign Cc: cba-news Subject: (cba:news) V405 Vul - superhumps have (fully) grown Dear colleagues, A first inspection of the light curve, resulting from my CCD photometry time series session of V405 Vul on Aug 29/30, 2000, clearly shows that superhumps have now strongly grown in this system. We measure a full superhump amplitude of about 0.4 magnitudes. Data were obtained using the 0.35-m f/6.3 telescope + unfiltered ST-7 CCD at CBA Belgium Observatory. Please remark the object is still bright tonight (Aug 30/31). We'll disseminate additional information about the present V405 Vul outburst, once we have gone through the analysis of the CCD data that we also received from other observatories. Kind regards, Tonny Vanmunster CBA Belgium Observatory