From jop at astro.columbia.edu Fri Jun 5 13:46:18 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Fri, 5 Jun 2020 13:46:18 -0400 Subject: (cba:news) v1223 Sgr Message-ID: <35ef842b-39ba-0eeb-270b-28eb9f85a657@astro.columbia.edu> Last night, Berto's and Josch's data on V1223 Sgr shows a single hours-long flare, about 1.8 mag in amplitude. Not previously seen in V1223. tt's known to be somewhat of an oddball among the intermediate polars, but this particular oddity - in amplitude and timescale - is not previously known in the class. Worth following up. joe p ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Thu Jun 11 17:26:14 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 11 Jun 2020 17:26:14 -0400 Subject: (cba:news) The month of HP Lib Message-ID: Hi CBAers, I'm getting plenty of data now on DQ Her, and have some very accurate pulse timings - enough to establish a very accurate phase during June 2020. It's time to put the star aside until october (late-season timings make it possible to ascertain a unique cycle count between one season and the next). The urgent need now is HP Lib. We are getting good coverage from Berto in South Africa, and from several European observers. But you norteamericanos - other than Tut Campbell - seem to be averse to that southerly declination. How scary can -14 degrees be? At mag 13.8 and with a 0.05 mag rapid oscillation, it's a pretty easy target for every observer. Long runs are nice of course, but anything >2.5 hours would be useful. As with AM CVn, HP Lib's main signal is a superhump - in itself, not all that interesting. But with a really strong campaign, we can subtract the superhump and find the weak orbital signal in the residuals. In addition, we can search for a negative superhump, like in AM CVn. It is such a dead ringer for AM CVn... I bet that negative superhump is in there, happy to emerge once our detection limits get just a little bit stronger! Later in the night, V1494 Aql and V1974 Cyg are definitely juicy targets for you northerners. More in a few days. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Thu Jun 25 08:08:35 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 25 Jun 2020 08:08:35 -0400 Subject: (cba:news) (cba:chat) ASASSN-V J205457.73+515731.9 of ATel #13824, anyone? In-Reply-To: References: Message-ID: <381e1023-1f15-d4d8-4d09-0bf0387d1229@astro.columbia.edu> Hi Heinz, Yes, now that I look over the information available so far, it looks like a star very much worth investigating - by us, as well as by other techniques (spectroscopy, astrometry, etc.) QPOs are certainly commonplace among CVs, but the photometric history and nearby nebula makes it extremely interesting. i think this should be a prime object for morning observing these days - although beware the crowded field! For now. Let's see if CBAers can get clean observations of this star. BTW my plaintive cry for HP Lib observations, especially in the north, met with a great response. We now have a sufficiently dense record to track that minuscule orbital signal. Some continued coverage is needed to track the relatively large (easy to measure!) superhump signal... but long coverage is not needed for that. joe p On 6/25/2020 6:46 AM, Heinz-Bernd Eggenstein wrote: > Hi all! > > I wonder whether anyone here has been looking at the CV candidate ASASSN-V J205457.73+515731.9 of ATel #13824,13825,13829 > > I have requested an AAVSO sequence for it which is now available. Note that the comp stars are all considerably redder, and also there is another source within only ~7" separation. It's an easy target at ca 14.5 mag (V). > > I've put my first obs data into the AAVSO database. Needless to say I cannot do any long runs on this (or anything else) from Germany at this time of year, but it seems obvious that there is very significant QPO-like variability on timescales of 10s of minutes, with a peak in the periodogram at ca 24 minutes. > > I certainly don't want to distract CBAers from program stars, I was just wondering whether this is an interesting target at all or just boring stuff (it seems to be in a relatively rare state now that might reveal things not obvious when it is in its usual state of stable accretion??, and because the authors of ATEL #13824 had doubts about its classification). I have two more short data stretches that I'll reduce soon. > > CS > HB > > > > ----------------------------------------------------------------- > Heinz-Bernd Eggenstein, Scientific Software Engineer > Max Planck Institute for Gravitational Physics > Callinstrasse 38 > D-30167 Hannover, Germany > Tel.: +49-511-762-17153 (Room 036) > ____________________________________________________________ > Center for Backyard Astrophysics (CBA) mailing lists > https://cbastro.org/communications/mailing-lists/ > ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/