(cba:news) stars for the new season

Joe Patterson jop at astro.columbia.edu
Tue Dec 18 12:24:05 EST 2018

Hi CBAers,

Getting ready for the solstice...

Stars ready to retire for the season:

RX J2133+51.  This is Enrique's guy.  I'll give him a chance to veto 
this... but methinks it's done for the year.

BW Scl.  We have plenty.  The runs are getting short, and the strangest 
feature seen in this star - the alleged "2:1 superhump" is muted this year.

T Pyx, believe it or not.  The season is just starting, but the early 
season coverage from the usual southern stalwarts (Josch, Gordon, Berto, 
Peter) showed that the star is exactly following its 2011-2017 ephemeris.

ES Cet.  Same story. keeping to its schedule.

ASASSN-18ey.  Of course.  It's in Aquila.  You can't get blood from a 
turnip.  Thanks to those (esp. Joe U) who battled evening twilight to 
get a few final magnitudes.

We seem to have become the world's major supplier of data in two 
categories: pulse timings of DQ Her stars, and orbital light curves and 
period changes in novae.  These are very much traditions worth 
continuing, and that goal strongly influences my recommendations for 
targets in this season.


Mainly the Puppis "gang of three" old novae: CP, HZ, and V598.  The 
second is magnetic, and the third probably is.  Time to get another 
season and get that into print.  CP Pup is the most mysterious, and 
amazingly resistant to surrendering its secrets to time-series 
photometry.  Probably it needs something close to round-the-world 
coverage.  Why?  See bottom of this message (technical reason, and not 
likely interesting to northerners)

Plus two DQ Her stars: V667 Pup and WX Pyx.


Mostly the DQs (intermediate polars) which have been previous winter 
targets: DW Cnc, HT Cam, V1062 Tau, V1033 Cas, V418 Gem, V647 Aur.

Let's suspend AT Cnc for now.  I'll have the analysis done by Jan 1, and 
we might resume.

Plus two northern stars which probably belong to the very exclusive 
"asynchronous polar" club: BY Cam and "Paloma" (5 24 30.5 +42 44 50)

Plus two other stars: the old nova T Aur
and the eruptive-and-seemingly-weird star ASASSN-18abl (03 00 55.08 +18 
02 29.0)

That's it for now!

joe p

CP Pup arcana. Its orbital frequency is almost certainly 16.32 c/d.  It 
has a photometric (and spectroscopic) signal at that frequency.  It also 
has an occasional big superhump at (I'm almost sure) around 16.05 c/d. 
That's pretty normal stuff.  But in the season of best coverage, the 
latter signal VERY STRONGLY favored 15.1 c/d, which is sort of a 
shocker.  The only sure way to beat a 24-hour alias is to have 
continuous observation over >24 hours... and the only way to do that is 
when the star is near opposition (Jan-Feb).  So you might want to keep 
your powder dry for a while.

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