From jop at astro.columbia.edu Sat Dec 5 08:50:54 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Sat, 5 Dec 2020 08:50:54 -0500 Subject: (cba:news) T Pyx 2020-1 Message-ID: <39e3f786-fb68-0e3e-c85a-a102552e4ad2@astro.columbia.edu> Hi CBAers, As many of you know, we have a paper on IM Nor/T Pyx about to go out the door (early version on astro-ph a few weeks ago). Although IM Nor is nominally the subject, the crux of the relevant physics lies with T Pyx, because that star's historical record is vast... and also because the analysis of IM Nor itself is greatly hampered by interstellar extinction. So even though we wrote a long paper in 2017 on T Pyx alone, it's time for another - because our audacious claims re the T Pyx/IM Nor phenomenon (runaway mass transfer, resulting in the binary's death) could use more scrutiny with new data. There are two important issues which our new observations could address: (1) Is the rate of orbital-period increase now the same as it was pre-outburst, or measurably less? (2) Has the star's brightness, averaged over many orbits, changed from the pre-outburst average? Sunce we observe it a LOT, we don't need a great deal of new data to address these questions. A few weeks of coverage will do it. Ideally the runs should be >2.5 hours long, and it would be best if you obtained some through a V filter, and some through your usual setup (probably unfiltered or some sort of minus-blue filter). The reason for the V filter is calibration, of course. The reason for some unfiltered coverage is to compare it with what you have done in past years. This sort of approach has a good chance to distinguish between the two leading interpretations: (a) T Pyx is doomed. (b) T Pyx is just having a bad coughing fit, lasting a few centuries. This interpretation has been advanced by Brad Schaefer, with some pretty decent evidence to back it up. Pyxis is usually reserved for southern observers. But at -32 degrees, this star is also fine for southern-USA observers, if you plan your observations around meridian passage, when the star is moving horizontally. Of course we always dislike airmass - but most of all, we dislike CHANGES in airmass. (And thanks to those of you who include airmass in their observing reports.) joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Thu Dec 10 06:57:50 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Thu, 10 Dec 2020 06:57:50 -0500 Subject: (cba:news) CC Scl in outburst Message-ID: <7857c317-fe5b-b7f9-2877-9522e6b0d98e@astro.columbia.edu> Dear CBAers, Peter Nelson's alert on this freshly-discovered intermediate polar was followed up by Josch. At 13.7, still plenty bright! The subject of outbursts in IPs is pretty murky. They don't seem to have much in common with true dwarf novae... but really, we just don't know. Let's try for a campaign. Sculptor is still available, and at -30 degrees still a viable target for some of the Norteamericanos. As well as the australites, of course. joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/ From jop at astro.columbia.edu Tue Dec 22 09:53:04 2020 From: jop at astro.columbia.edu (Joe Patterson) Date: Tue, 22 Dec 2020 09:53:04 -0500 Subject: (cba:news) ah men, v902 mon, and the puppis crew Message-ID: <9d9ebf39-c050-deac-62f1-6a02fa1ade0a@astro.columbia.edu> Hi CBAers, Time for some changes in the southern sky. 1. We can end the season on AH Men, the very bright and very southern novalike. We have some nearly round-the-world coverage, and the dominant periods are well-defined... with the most powerful being a negative superhump near 3 hours. 2. Puppis is chock full of interesting novae. The most famous is CP Pup; we have a lot of data from past years, and the variability is REALLY hard to decipher. So just pay it a visit to see if it's straying from its usual magnitude near 15.5+-0.5. 3. V597 Pup. Really interesting 2009 MNRAS paper by Warner and Woudt. Very likely an IP, and an orbital light curve reminiscent of T Pyx. Probably fainter than 18.5 and a somewhat difficult field... but have a look and see if it's feasible. If so, let's make this a major target. 4. HZ Pup. We basically worked out the ephemerides (orbit, spin) last year. But the true test is whether an ephemeris can predict thousands of cycles later... so this is a good target for about a week of dense coverage (I'll analyze and call the campaign over if the ephemerides are good). 5. V598 Pup. We also have very good timing data on this old nova, but there are so many peaks in the power spectrum - which makes for ambiguity. Until further notice, this 16th mag star is a major target for Dec-Jan (at least) 6. V902 Mon. Richard Sabo (Montana) has been working brilliantly on this recent nova, but with the equatorial location, we certainly need coverage from other longitudes. BEAUTIFUL eclipsing IP. You gotta love this one. 7. BT Mon. Yet another nova... and in this case our ONLY interest is the deep eclipse. The period is very close to 8 hours (0.3338139 days), so you may or may not have an eclipse in your observing window. Here's a rough ephemeris: HJD 2,443,491.72 + 0.3338139 E. A few 2-3 hour observations including eclipses will sharpen up the orbital ephemeris (which appears to show a surprisingly large dP/dt). joe ____________________________________________________________ Center for Backyard Astrophysics (CBA) mailing lists https://cbastro.org/communications/mailing-lists/