(cba:news) CBA targets, at last...

Joe Patterson jop at astro.columbia.edu
Wed Nov 7 08:01:41 EST 2018

Hi CBAers,

Apologies for being so silent for so long, re targets.

Naturally, it's all a black hole's fault.  Since our data on the new 
X-ray transient - the brightest in history, I believe - started piling 
up in April, I became enthralled by its developing 17-hour superhump. 
We acquired ~2000 hours of data on it, and have tracked the phase 
faithfully, never losing cycle count, for 6 months.  Attention to the 
rest of the Universe suffered (stars, but also laundry, dog, 
bill-paying, etc.)  But now the western twilight has pretty much 
swallowed up ASASSN-18ey, and it's time to get back to the rest of the 
starry sky.  Through your data, I also became acquainted with some 
bright new stars in the CBA firmament.

A whole new set of stars (many old friends, but with important physics 
issues outstanding) has rolled around.

1. RXJ2133+51, Enrique's star.  Extend that cycle count until the end of 

2. T Pyx.  Definitely!  A;though we published recently, a 
still-unclarified issue is: does the post-eruption dP/dt really equal 
the pre-eruption dP/dt?  I believe the answer is yes, but still 
unproven.  It matters a lot, because it impacts the question: is its 
dP/dt a steady headlong and frantic rush towards suicide... or just a 
funny wiggle in a mysterious star?

3. BW Scl.  The great exemplar of a superhumper with a huge period 
excess - just barely reported on, thanks to my negligence.  Great and 
decently bright southern target.

4. CP Pup.  Basically the same type of beast, but not reported on at 
all, thanks to my UTTER negligence.

5. ES Cet.  We published our detection of a Pdot, very important since 
even the *donor* star is thought to be degenerate (and thus possibly 
immune from the "magnetic cycle" excuse for orbital period  changes).
Nice all-hemisphere target.

6. V1062 Tau and AT Cnc.  Likely and possible DQ Her stars.  Not yet 
written up by us, waiting for one more good season.

7. QR And. Is its period really changing fast, like all the other 
supersofts?  (ALL of them!!)  One more season will probably answer this.

8. V959 Mon.  Let's keep tracking that post-eruption orbital period.

9. Finally, for those of you who have persisted with ASASSN-18ey, see if 
you can drag it out two more weeks.  The star is fading much faster now, 
and that timescale of fading may prove a good number!  (But when you can 
only get 1 hour, THEN quit; the *random* variability will then kill you.)

All of these are regular CBA-style observing projects - long time series 
highly favored, and unfiltered is usually the right choice, unless you 
have photons to burn.  The usual rule applies: V filter better for 
archiving, and unfiltered for the actual time-series studies.

    That's the menu.  I'm looking forward to seeing a bunch of you at 
the AAVSO in Flagstaff.  Maybe we can concoct a trip to Sunset Crater on 

joe p

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