From jop at astro.columbia.edu Mon May 2 07:59:30 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Mon, 2 May 2005 07:59:30 -0400 (EDT) Subject: (cba:news) stars for early May Message-ID: Dear CBAers, Now it's time to get the CR Boo campaign in high gear. It's accessible to all hemispheres, most of the night, and presents some of the most interesting light curves in CV captivity. We hope to cover the star through a full bright-faint cycle, which is probably near 50 days. We have two other northern targets. LX Ser is an eclipsing well-placed star which we have observed on one previous occasion - finding no superhumps (although the orbital period is suggestive of superhumps). We should definitely try again - in the usual manner of very long time series. The other is RX1643+34 - "Her" in the Downes et al. catalog. This one we've also done, and have found superhumps. Tracking them over a long baseline should be very interesting. But of even greater interest are the 20 minute quasi-periodic oscillations - the strongest and most coherent of all the QPOs seen in CVs. RX1643 is not quite in prime season yet, but some early May nibbles on it would be welcome. In the south, it's V504 Cen, as well as CR Boo which should be mighty accessible at +8 degrees. BTW, I've decided to go to the Big Bear IAPPP meeting. With golf clubs too. Hope to see some of you out there! joe From jop at astro.columbia.edu Thu May 12 06:09:04 2005 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 12 May 2005 06:09:04 -0400 (EDT) Subject: (cba:news) targets new and old Message-ID: Dear CBAers, Just a quick note before jumping on a plane to AZ. The V504 Cen campaign has been... well, spectacular. Probably the best-covered star since WZ Sge in 2001. However, I haven't been able to keep up with the data flow. From the analysis so far, it looks like there are signals near 5 hours and 45 minutes... although in both cases there's doubt about their stability. Anyway, after 12 days of round-the-world coverage we've reached a detection limit we won't be improving with more coverage. So it's best to end the campaign and transfer all that good mojo to another star! My prime recommendation is V803 Cen. The exact values of Psh and Porb in this star are still not known to satisfactory accuracy, and the exact sequencing of high state - low state - oscillating state is also not securely not known. The star varies between 13 and 15.5, with a few brief excursions to 17. Should be accessible to you in all states, and is a super-high priority when it's around 13.0. Secondary southern target is EX Hya. No coverage yet this year, and somewhat neglected by us always. It's just a little late in the season, but well-suited for the next 3 weeks, and relatively immune to moonlight and similar afflictions of the night. Time to catch that plane. Comments on northern targets coming from AZ Saturday. joe