(cba:news) V378 Peg, mainly; also RX2133+51, V1294 Tau, and QR And

Joe Patterson jop at astro.columbia.edu
Wed Oct 9 20:01:15 EDT 2013


Dear CBAers,

One big subtraction in the menu.  We'll back off of RX2133+51, unless 
Enrique changes his mind.  It has been mighty good to us, and has taught 
us that negative superhumps are not particularly rare in magnetic 
systems.  Now that we know that, we'll look more vigorously!

I'd very much like to promote V378 Peg as a principal northern target 
for the next month or more.  Ringwald and Kozhevnikov have found 
superhumps in it, and it seems likely from Enrique's first night that 
they're still rolling through the light curve.  Looks like a decent 
match for V603 Aql, which gave us simultaneous negative and positive 
superhumps - and enabled precise measurement of both.  Large amplitude, 
decently bright star, well placed in the sky, and never targeted by us. 
  It is high time to fix that latter oversight.

QR And is another good northern target.  This is a well known supersoft 
source, one of just a few known in the Milky Way.  We basically want to 
track its eclipse minima in order to measure its rate of period change. 
  The empirical rates in the supersofts generally are impressively high, 
and indeed I suspect that to be one of the key signatures of a supersoft 
nature, even when the obvious evidence of its nature (the X-rays 
themselves) is lacking.  That'll take a heap more work to evaluate, 
though!  At 16 hours, the period is kinda long, so you'll need to 
patient on this guy; but at 12th magnitude, it's friendly to small scopes.

Finally (in this note), I did a quick evaluation of the V1294 Tau data. 
  It does appear that the strange periodic structure we saw in 2002 is 
still there.  I do have some doubt about observing it in early October 
though.  As an equatorial target, no one can get really long runs on it. 
  So maybe we should wait for it to get more central in the observing 
season (a month from now).  But on the other hand, maybe you like 
Taurus.  If so, keep the faith on it... and it would be great if some of 
our australites - commonly loath to turn their scopes north of the 
equator - pitched in.  Especially in AU/NZ, where we otherwise suffer 
from a big "Pacific gap".

Don't forget ES Cet!  Very rewarding star for time series: a beautiful 
light curve you can send home to Mom and Dad!  And do it repeatedly, 
because the error gets smaller with with each observation, unlike 
typical CVs where flickering always dominate the errors.

joe
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