(cba:news) stars for January

Joe Patterson jop at astro.columbia.edu
Sun Dec 31 12:43:32 EST 2000

Dear CBAers,

  Weather has been a big problem with RZ Leo observations, but we've had
enough contributions from Europe (Tonny) and North America (Dave East,
James Hannon, Brian Martin) to define the star's main superhump period.
It reports in at 3.4+-0.2% longer than Porb.  This is something of a
surprise, as most of the infrequently erupting SU UMas have much smaller
period excesses, signifying a light secondary (a few even with M2<0.08
Mo). C'est la vie I guess.  If we can get enough more coverage, we might
be able to track the Pdot and measure the amplitudes of the
quasi-harmonics; these give valuable (though not presently
well-understood) information about changes in the accretion-disk

  So RZ Leo continues to be a great target for all imaginable hemispheres.
Track it into the mud.

  BZ Cam, now there's a different story.  BZ Cam is very bright this year,
and doesn't show much activity on ~3-hour timescales.  I think we should
lose this star from our target lists.

  Brian and Tonny have been observing UV Per, another rare erupter which
followed RZ Leo into outburst.  This is a good northern target for as long
as it's bright.  The main superhump period is known, but we can greatly
improve on its accuracy and study upper harmonics.

  Then there are the DQ Hers (the second line of the "Current Targets"
list).  Old friends that are always happy for visitors, and will reward
you too.  But you gotta know - and more especially your computer's gotta
know - the time to within 10 seconds or so.  1-900-410-TIME is worth

  Now for the south.  Unnnh, I could hardly overstate how psyched I am
about TW Pic this season.  Robert Rea, Jennie McCormick, and Fred Velthius
have been following it, and finding these long, slow waves which are quite
big and obviously signify a strong periodic signal.  Unfortunately all the
observations are from NZ (no, make that one from AU - Gordon) and the NZ
weather has been none too good.  So we are really, really hoping to redeem
all this great data with more frequent coverage, especially at other
longitudes (but  NZ too!).  Any help you-all can provide would be great.

  I was also hoping to begin the T Pyx season now.  This star is 15.3
and has a very periodic 0.0762 d signal, which we have been tracking
for 4 years.  The period is changing remarkably fast, and we need to
get some densely spaced coverage every year to maintain cycle count.
The light curve doesn't *look* like much, but it's practically a unique 
star - a short-Porb CV blowing itself apart on a timescale of 10
million years!

  Happy observing north and south.  I hope to return with CBA converts
from Golconda and the mystic East.


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