(cba:news) stars for the new season (Joe Patterson) [2011-12-26T03:21:38Z]

                                                     25 December 2011
Dear CBAers,

     Merry Christmas, everyone!  It's a new sidereal season, too.  Time
to say goodbye to some of our long fall campaigns - esp. BW Scl, V378 Peg,
and CD Ind.  For those of you who participated in these campaigns, and
who might like to take a crack at analyzing the data - ask!

   Except for a few DQ Hers (for which relatively short runs are still
useful), stars in the RA range 19h -> 2h should probably be ushered off
the stage.  And let's also suspend BY Cam, not for poor performance,
poor coverage, or lack of seasonality (it's superb in all those areas)...
but just to give some room for other deserving stars!  (The BY Cam
campaign is already 80 nights long.)
                                                    
   Now for two campaigns we *do* want to continue.  

1. Josch Hambsch has been carrying out a close but solo vigil on TV
Columbae.  This star is crucial for the question of "how long a Porb for
apsidal superhumps?" and "effect of magnetism on disk stability".  It's
a candidate for apsidal superhumps (claimed period 6.3 hours).  The
seasonal timing is excellent for Columba, but summer nights only permit
brief runs.  That, plus the awkwardness of 6.3 hrs (too long, too easily
aliased), makes multi-longitude coverage MANDATORY.  So this is a very
high priority target for other longitudes (South Africa, AU/NZ)... and
continued observation from Chile.

2. "Paloma" (RX0524+42) is a pretty good candidate for an asynchronous
polar.  Enrique and Tom have been actively observing it... but the
campaign definitely needs help  - and also length.  The star is quite
faint (about 17.3), but typically has a very large amplitude (1 mag).

    Mainly, though, we want to start up several new campaigns.  Basically
all these are in the "negative superhump" category - either revisiting
a star that showed such a signal in a previous campaign, or launching a
first-time search for signals.  In all cases, quite long nightly time
series are very desirable.
     
1. KUV0358+06 = TAU 2 = SDSS0400+06 = (I think) V1294 Tau.  We did one
previous campaign on this star, and it revealed signals slightly shorter
and longer than Porb (as well as Porb).  This is a rarity... but what
really surprised me was the epsilon (the percentage displacement of the
signals from Porb).  It was just half of what's expected, based on Porb.
Southern Taurus is well placed again, and I'm hoping for some
contributions from AU/NZ - these would eliminate any potential confusion
due to aliasing (more worrisome here, since there are *three* closely
nested signals).

2. AH MEN.  Definitely.  Past campaigns are consistent with the same
result (positive and negative superhumps), but aliasing is problematic.
In theory we should be able to get round-the-world coverage: Chile, NZ,
AU, South Africa.  That'll clobber those aliases!  Note: this is quite
a bright star, but has a contaminating neighbor about 3-4 arcsec away.
Probably it's best to measure the two stars together (aperture photometry),
and for some night of excellent seeing and small image profile, measure
the relative contributions.

3. IM ERI (0424-20).  Nice bright star, eclipsing, superhumps.  Same
story - very good target, and to combat differential extinction, V
observations are recommended (if you can tolerate the light loss).

4. ER UMA and BK LYN.  Enrique has started up these campaigns.  Both
stars have negative superhumps, and we are trying now to study long-term
timing effects of this signal.  They're *slightly* out of season, but
several-hour time series now, followed by *really* long ones in Jan/Feb,
will properly test the stability of these signals.

     Finally, there's T Pyx.  The actual slow decline is being well
documented by many people.  But we need time series to define Porb
as accurately as possible - that means fairly long nightly time series.

    There's the desiderata.  Happy observing!


    joe