

                                                     28 January 2012
Dear CBAers,

The new semester has started - and it's been a scramble to keep up with
all your data.  Here's the status of the leading stars.

1. RX0524+42 = "Paloma".  Our 60-day campaign, primarily by Enrique and
Tom, has been just superb.  At least 15 different frequencies present in
this remarkable star.  What is it?  The *basic* periods are 2.62 and 2.27
hours, and others can be represented as linear combinations of these
frequencies.  It's possible that the star is a "missing link" between AM
Her and DQ Her stars - with these periods being the orbital and rotational
periods.  Maybe... but one can also represent the signals as disk precession
signals, with a very unconventional ratio of periods.  So far, our
observational skill has outraced our skill in undertsanding such things.
Time to ring down the curtain and publish the thing.

2. TV Col.  Nearly 60-day campaign, led by Josch and Berto.  The star
showed both the orbital and (presumed) negative-superhump signal, various
high harmonics, and a new signal at the lower nodal sideband of the X-ray
pulse period.  Apparently the best campaign ever, the first to show that
last signal, and sufficient to establish long-term ephemerides.  No sign
of that at-least-transient-and-maybe-not-real 6.3 hour superhump.  That's
good enough - take it off the menu.

3. BY Cam.  Now the campaign spreads over 120 days, long runs all.  Whew;
this is one star where I'm way behind on data analysis.  On humanitarian
grounds, and also to clear the decks for other evening stars, it's a good
time to end the campaign.

4. IM Eri.  Nice bright star, with well-behaved negative superhumps.  (Not
eclipsing, as I mistakenly said earlier.)  Good campaign, but practically
everything from the Americas.  Good for small scopes everywhere, but
especially from Europe and AU/NZ.  (Not to mention much-coveted but
still-unattained East Asia.)  We have 27 days, would like another 10.

5. AH Men.  Pretty good coverage all around, especially from Josch.  One
of the two superhumps is evident.  However, the signal is quite weak
this year, and it could be a struggle.  Another star to suspend.

6. KUV0358+06 = TAU 2 = SDSS0400+06 = (I think) V1294 Tau.  Hardly
anyone took this suggestion... maybe cuz it was too late in the season.
Anyway, it definitely is now - so forget this star.


Now for some stars still going quite strong, or new entries.  Not in
any particular order.

1, 2. ER UMA and BK LYN.  These stars are showpiece superhumpers.  ER UMa
has both positive and negative superhumps, and a season's coverage will
encompass many normal outbursts and a few supers.  This gives numerous
opportunities for the various superhumps to change period and amplitude -
and thereby inform us about the effects of outburst state on hump signals.
Only once before have we had such an opportunity (V503 Cyg)... and it
would be awfully nice to know if the pattern in that star is universal.
The story in BK Lyn has some element of this (it had an outburst 2 weeks
ago, at the beginning of the campaign)... but the main story is the
large amplitude and apparent stability of the (negative) superhumps.  The
stability might well be high enough to count cycles from year to year;
that would be nice to know (and damn puzzling if true).

3. V1193 ORI.  Alex Liu found some nice negative superhumps in this star
back in 2005; we did too, but didn't publish.  A month of 2012 coverage
will complement our old data nicely.  The star is slightly out of
season, but since it's exactly on the equator, we should be able to
splice together many longitudes to get a good global light curve.  (Liu's
coverage was marred by having only one longitude, though our simultaneous
study shows that he got the cycle count right).

4. V393 HYA.  Another of our unpublished (negative) superhump detections.
Getting in season - let's get at least a month of 2012 data to book-end
with our 2005 results.

5. CP Puppis.  If only!  This celebrated nova has large-amplitude 90
minute waves... but what are they?  They change drastically in amplitude
and phase from night to night, and no one has ever figured out why.
Or even what the signals are.  Years ago I made the default (and lame)
suggestion "orbit and superhump".  That works if you only have a little
data - but falls apart if you get more.  It's more complex.  The signals
can only be tracked by a round-the-world campaign, and I'm pleading for
this as the top priority for our southern observers.  CP Puppis is one
of the most famous, fastest, and best-studied novae - and one of the
very few below the period gap - but continues to taunt us with these
large and mysterious waves.  Let's strike a blow for human understanding.

6. 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.  We already have two good detections
in early season; so I'd suggest suspending for now, and resuming in March.

7. AM CVn.  It's time to resume coverage of this old favorite of ours.
The unresolved questions are: (1) does Porb secularly decrease, as
the long-term pattern suggests; and (2) do the period changes of nodal
and apsidal humps track each other 180 degrees out of phase, as expected
from intuition?  And is there a weak signal at the putative nodal
precession frequency (0.31 c/d, expected from theory)?  It's early in the
season, but the season *needs* to be long to answer these questions.

8. V355 UMa = SDSS1339+48.  Now nearing quiescence (17.2) after its big
superoutburst.  Enrique has resumed coverage, but we definitely USA
coverage to complement his.  The basic question is, what does an
intrisically faint binary look like a year after a big outburst - and
in particular what is the white dwarf doing?  Quite a faint star - not
for everybody.

9. The DQ Her menu, and especially ones with no coverage this year:
BG CMi, PQ Gem, HT Cam, DW Cnc (long runs only), WX Pyx.

10. Finally, as a class there's "new and interesting dwarf novae".  I
don't list many of 'em in these messages, since others are doing a
fine job on 'em - and since many of you have a very keen sense of what's
interesting: the brightest ones, the rarest ones, etc.  Especially the
"first eruption ever" guys which are bright (say brighter than V=11) -
these are damned interesting, but rare.
                                       

    Thus the desiderata.  A lot here - you can't blame a guy for
wishing!


    joe
