(cba:news) stars of february

Joe Patterson jop at astro.columbia.edu
Fri Feb 18 18:58:54 EST 2000

                              2/18/00 - first day of being 53; kind of
                              a boring number (does anyone know
                              anything interesting about this number?)

Dear CBAers,

Time for some major talk about targets.  A lotta stuff poppin' off up
there, things are getting confusing.  Here goes.

FS Aurigae.  Still a mystery star.  But we've gotten only a little
this year, and there are too many other evening targets we need to
cover to achieve success.  Time to end this campaign I think.

BY Cam.  Brian Martin and Dave Skillman have covered BY Cam
extensively, and with the far-northern dec we can still get long runs.
So I reckon this one should have a very high priority.  Do it
repeatedly!  The star often (but not always) has very wide excursions
in light, which we need to follow to track the periodic behavior
properly.  Brian, I think we'll throw this project your way, if that's
agreeable to you.

RXJ0909.8+18somethingorother.  Another mystery star, not yet clear what
box it belongs to.  Or maybe a box all its own.  The advantage here is
the deep eclipses - no big mystery should endure when you have the
diagnostic power of eclipses!  Tonny and Gordon have been following it
pretty well, and Tonny will write up the results.  It's about 16th mag
now, sort of borderline for most of you.  In a week we start a run on
the 1.3 m, and we'll devote it heavily to RX0909.  Tonny, why don't you
send out the requests for observations?  My guess is that it doesn't
need more small-scope attention unless it erupts again; but I might be
wrong, so it's your call.

RXJ0459+somethingorother = Tau 3.  A little dwarf nova which several of
us have been observing, including Gianluca Masi and Gordon.  Gianluca
is writing up the paper.  The star has disappeared from most of our
screens, though we'll try a minimum-light study during the 1.3 m run
next week.

SW UMa.  Damn thing erupted to 11th mag at a perfect time, transiting
around local midnight.  The 1987 Texas study (Robinson et al.) was I
thought quite good and not in need of improvement.  But some recent
light curves I've seen from Jochen Pietz and Brian Martin in the
present outburst are so excellent that I now think we can learn a lot
of new stuff from SW UMa.  Some oddities are hanging around from the
1980s outburst (funny Pdot, anomalously high period excess of the
superhumps), and it's time to study 'em more.  So I now think we
borealites should go pretty hard on it.

CN Ori.  Very fine contributions from New Zealand coming in on this
star.  But to break aliases, we now have to make sure that we have
coverage from other longitudes!  Any Orion fans out there?  One more
month on this guy.

IY UMa and DV UMa.  Totally fascinating stars, but off the small-scope
radar screens unless they rise again.  New results up on the website.

RZ LMi.  I took it off the menu, it keeps getting overshadowed by
eruptions of other stars.  Still some life left in the observing
season, so we expect to pick it up again soon.

U Gem.  A long-term project, let's not forget it.  4.2 hour light
curves are always valuable as the eclipse will trace the brightness
and location of the hot (bright) spot every time around.  We want to
follow this around the ~100 day outburst cycle; it's critical since the
bright spot is the direct signature of the immediate mass-transfer
rate, and nothing else is (once the matter settles into the disk, it
gets modulated by the largely unknown vagaries of disk physics - but
the bright spot is a simple GMMdot/R splash).  Within a few weeks it's
likely that U Gem will erupt again, and that's the time for concerted
tree-to-tree observation because the spot structure should change
*drastically* then.

Summary: SW UMa, CN Ori, BY Cam, U Gem are the major dramatis personae,
pending further surprises of course!


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