(cba:news) august stars

Joe Patterson jop at astro.columbia.edu
Sun Jul 29 23:12:28 EDT 2012

Dear CBAers,

New month, new lunation... time for changes in targets.

It's time to end V1432 Aql.  Thanks to Josch, Bob Rea, and David Boyd, 
we now have one complete supercycle (50 days) covered, and it's easy to 
derive ephemerides for the orbital and rotational signals.  And we even 
have a highly accurate estimate for the synchronization time: 103+-4 
years.  Hallelujah... and we're done with it.

V503 Cygni has been problematic - just one superoutburst seen, and hard 
to track the quiescent signal given the star's faintness and 
predilection to have "normal outbursts" (which dilute the periodic 
signal). Let's suspend until further notice.

IX Dra could be a very good target, but this notice comes a tad late to 
take advantage of its present super.  If you have some not-yet-sent 
data, cough it up pronto!... otherwise we'll suspend this one too.

It's time to get eclipse timings on two bright "V Sge" stars; namely V 
Sge and V617 Sgr.  These are bright targets and a straightforward 
science program - to measure the Pdot, which should be a measure of mass 
transfer in these very luminous binaries.  Good targets to fight the 
current nuisance of Olde Whiteface up there.

Good northern targets for whole-month and long-night coverage are these:
1. GD 552 ("Cep 1" in Downes et al.). One of the nearest and probably 
oldest CVs.  The pattern of variability is still not well known.  The 
light curve is no barn-burner, but we very much want data right now to 
slap onto a paper now 98% written (reporting many other types of data 
over the past 12 years).  Usually at magnitude 16.6.
2. RX2133+51.  A DQ Her star with a mysterious periodic signal 6% 
shorter than Porb (as well as a fast signal qualifying it for DQ Her 
membership).  Let's solve that mystery!
3. V1315 Aql.  An eclipsing SW Sexer with quite a rich spectrum of 
periodic signals.  We've never quite got enough to complete our study; 
let's do it this year!
4. BW Scl.  What is this delightful star doing now - now that it's had a 
while to cool off after its historic eruption?

There are a LOT of DQ Her stars up there which could profit from 
scattered coverage: AO Psc, IGR 1654-19, V1223 Sgr, V1033 Cas, 
XSS0056+4548, V455 And, and especially V4743 Sgr.  In fact the latter 
could be considered high priority - though difficult.

Finally, there's CD Ind - another "asynchronous polar" (like V1432 Aql).
We're sort of specializing in these guys; they're perfect for the CBA 
since we're about the only people who can measure these slow and small 
period changes. We did a great job in 2011 - let's seal it up with 
coverage this year.

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