From jop at astro.columbia.edu Sat Aug 2 20:51:06 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 02 Aug 2014 20:51:06 -0400 Subject: (cba:news) more on novae and DQ Hers Message-ID: <53DD877A.8010108@astro.columbia.edu> Update from the last message. DQ Her. Another week of time series from David Cejudo has nailed down all the features potentially extractable from the light curve, including the spin period to an accuracy of a few microseconds (because the long-term ephemeris is specified). So we're finished with DQ Her. V1494 Aql. Wow. The new coverage from Jim Jones and Gordon Myers has now established how intricate is the spectrum of periodic signals. Apparently there is a "negative" or "nodal" superhump, as well as the nodal frequency itself (0.44 c/d), and some other high-frequency stuff in the vicinity of 3 w_orb. Quite a haul... and accompanied by deep eclipses, which could enable us to figure where in the binary these signals come from. The signals appear to be well-established, but the star is faint and somewhat troubled by a crowding star (include it in the aperture); so we GREATLY desire more coverage - the longer the better. Please keep the faith! About 16.9 magnitude. V339 Del and HR Del. The Dolphins are easy to do - both being about mag 12.5. But so far, the light curves don't reveal periods; they're not long enough, or not of sufficient signal-to-noise. There's a tentative suggestion of a 6,5 hour period in last year's V339 Del data... but it's not really evident this year (so far). Quite a tough star To do it, you need to reduce your internal noise down to 0.02 mag (and preferably 0.01 mag). HR Del is not as demanding, but it does require long runs - plus, it's quite speculative. But V1223 Sgr is a great target, and really needs more coverage from all longitudes. It looks like the star is flashing a superhump for the first time - but multi-longitude coverage is usually critical in establishing this. Very high priority. \ And now that August has arrived, it's time for early-season coverage of V410 Cas and V455 And (very fast photometry needed) - as well as V2306 Cyg and RX2133+51 in the midnight sky. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Fri Aug 8 07:27:24 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 08 Aug 2014 07:27:24 -0400 Subject: (cba:news) CSS J174033.5+414756 outburst! In-Reply-To: References: Message-ID: <53E4B41C.7050900@astro.columbia.edu> Dear CBAers, This quite strange star is again in outburst. While it is possibly a "short outburst" - without any definite model implies by this term! - it's far too interesting to pass up. Let's jump on it right away! My notes say that the preferred comparison stars (used last year) are: JJ: 000-BKZ-140 (V=13.761) EA: GSC 3096-1994 (V=13.441) I even think that this is now the *top priority* target for northerners. Much as I love V1494 Aql and all the great data you guys are getting, I think this one is more important and time-critical now. The novae can wait a little bit. But - just to stay reasonably loyal to classical novae - I wanted to endorse V4743 Sgr again (so far only Berto has observed it this year), and also V1974 Cyg (pretty faint, so you might want to wait for good conditions). joe -------- Original Message -------- From: Denis Denisenko To: vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp Content-Type: text/plain; charset=UTF-8 Subject: [vsnet-alert 17610] CSS J174033.5+414756 outburst X-DSPAM-Signature: 53e4a177220533702315154 This very unusual large amplitude (~7m) short-period (65-min) dwarf nova in Hercules is in outburst! Last negative observation was a week ago. CSS J174033.5+414756 (ASASSN-13ae) 20140730.120 <142V C. Chiselbrook (AAVSO) 20140806.109 138V C. Chiselbrook (AAVSO) 20140806.993 13.98V J.-L. Gonzalez Carballo (AAVSO) 20140807.087 139V C. Chiselbrook (AAVSO) 20140807.157 13.77V J. O'Neill (AAVSO) Light curve of CSS 130418:174033+414756 from Catalina Sky Survey: http://nesssi.cacr.caltech.edu/catalina/20130418/1304181400734166981p.html Previous outbursts: 2013 Apr. 18 (discovery by CSS), 2007 May 15 (found post factum in CSS data). There was extensive observing campaign in April-May 2013 following [vsnet-alert 15629]. The photometric behavior (~50 days long superoutburst and evolution of superhumps) plus presense of Hydrogen lines in spectra allowed to classify the star as UGWZ dwarf nova. The period around 0.045d makes it an extremely unusual object. Yet now we have an outburst just 15.5 months after the previous one! Denis Denisenko ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Sun Aug 17 19:34:32 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Sun, 17 Aug 2014 19:34:32 -0400 Subject: (cba:news) v1101 aql, v1974 cyg, v1494 aql, cc scl, GD 552, V1223 Sgr Message-ID: <53F13C08.6000804@astro.columbia.edu> Dear CBAers, Time for a report on targets. We've gone 33 days, missing only 3, on V1101 Aql... and the light curves are beautiful. However, the star is about to rise from 15.5 to its high state around 13.9 - and we've never really caught the transition (it seems to occur in ~1 day). We need to stay on this star just ~4 more days to be sure of catching it. Kudos to Tomas Gomez and Joe Ulowetz for doing the heavy lifting on this star! The coverage on V1494 Aql has also been superb. The orbital waveform is very well defined, including the eclipse, and a superhump has appeared. BUT there's an interloper star just 1.5 arcsec away from V1494 Aql. We can't distinguish it, but we can try to minimize it by using a B filter. The critical need is to find out just how deep the eclipse is. It's mighty deep; the star is somewhere around 18.5 mag at mid-eclipse. A few decent eclipses will do the job, if you can manage at that brightness. With our recent stress on classical novae, it's time now to do V1974 Cyg (+ N Cyg 1992, the "nova of the century"). Especially now, in the dark of the moon. Another tough target - 17th mag - and we need a several-week campaign. The idea is to measure the phase of the orbital signal; it's pretty subtle, normally dominated by the superhump - but with enough coverage, we should be able to extract the orbital wave (about 1.9 hours). Long runs needed, clear filter. And finally - for the north - there's GD 552 = Cep 1 in the Downes et al. catalog. About 16.4, and we've never managed to catch the orbital signal. And, for that matter, neither has anyone else. Probably the oldest CV in the sky. In the south, we want to continue on V1223 Sgr and CC Scl, and start up a campaign on VZ Scl (already started by Gordon). Then there are the dwarf novae. I'll study them and comment later! joe v1494 aql - b, v1974 cyg v1101 aql cc scl gd 552 cep 1 ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Tue Aug 19 02:52:35 2014 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 19 Aug 2014 02:52:35 -0400 Subject: (cba:news) August/September easy northern targets In-Reply-To: References: Message-ID: <53F2F433.70909@astro.columbia.edu> (cc-ing to cba-news since it's of possibly wider interest) The two obvious choices are FO Aqr and AO Psc, since they're bright and the period of interest is very short (mainly the spin periods of 21 and 14 min). And we have basically not visited them in 2014. If they're a tad too low or too south for short evening runs, then do V Sge. The period is long, but we can synthesize the orbital light curves, and hence the eclipse timing, from sequences of short runs. Some qualifiers: 1. AO Psc is in a remarkably sparse field. 2. V Sge is ~11-12 mag and can be done with a V filter; could that be why it's called a V filter? The light curves of each are sufficiently well known to allow accurate evaluation of data quality - yet the long-term period changes are of great astrophysical interest (and they're accessible to our decades-long observing programs). joe On 8/18/2014 4:21 PM, Jonathan Kemp wrote: > Well, our little CCD saga continues. Finger Lakes can't fix our old one, > but I'm testing out a backup camera and might go on sky with it soon. > Any CV target recommendations for short-ish evening runs over the next > couple of weeks? > > Jonathan > ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/