(cba:news) RZ LMi, mostly... and some other March-April targets

Joe Patterson jop at astro.columbia.edu
Fri Mar 25 04:53:11 EDT 2016

Dear CBAers,

It's time for us to get back to RZ LMi, one of our common Feb-Apr 
targets of 5-10 years ago.  It's the most frequently outbursting of the 
most frantic dwarf-nova class of them all, the ER UMa stars.  No one has 
ever managed to learn its precise orbital period, since spectral 
features are extremely weak and not necessarily stable... and since it 
spends so little time at anything resembling "quiescence".

This and other recent vsnet posts about this star do not necessarily 
indicate anything unusual - we've been misled and foiled by this star 
several times before!  But it *might* turn out to be a true and 
long-lived standstill, and that would finally give BK Lyn a much-needed 
cousin in the sky (as presently the only such short-period star).  It's 
definitely worth another try.  Decently well-placed in the evening sky.

And I'd say the same for V803 Cen, too, though with less confidence that 
its present behavior is anything unusual.  Let's jump back on this star 
for at least 2 weeks or so.

IM Nor is wrapped up for the year.  The eclipses are stable and verify 
the huge Pdot we found in last year's study.  A true counterpart to T Pyx!

The AM CVn coverage has been really good - magnificent!  The main goal, 
studying the weak orbital wave for its precise timing, has been met.  So 
on general principles, it's probably time to quit.

Maybe Enrique can comment on AT Cnc.  It has a persistent short period, 
but so far, my analysis suggests that it's a quasi-periodic oscillation 
("QPO") rather than the *stable* short-period signal that we always 
treasure greatly.  Hard to be sure.  If it is a QPO, it's the most 
stable of the QPOers - but even that would be millions or billions of 
times less stable than a true DQ Her star!  I'm tempted to say that AT 
Cnc season is over... Enrique, whaddayathink?

DQ Her (intermediate polar) observations are always valued, and Koji 
Mukai's webpage is always the best source for thius class:


More in a day or two.

joe p

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RZ LMi: still in superoutburst

    Kiyota-san, Geoff Stone have reported new time-resolved
observations.  Enrique de Miguel has supplied snapshot
observations.  The object is still in superoutburst
(at least on Mar. 24).  The mean magnitude has been
almost constant since Mar. 13 and the light curve even
looks like a standstill.  Superhumps are still present.
Let's see what happens next!

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