(cba:news) half man, half beast, and half dwarf nova?

[Joe Patterson]

Dear CBAers,                                             April 6, 1997.

     Well, our first observing run in South Africa has been tough.  So
far, only 3 half nights have been good out of 13.  Plus a few scattered
hours.  We have 8 more nights scheduled, so we remain gallant and ready
whenever clear weather strikes.

     Still, we've learned some things about V803 Cen, our primary
target.  First, the S. African data was showing steady upward and
downward ramps lasting for many hours, much like CR Boo.  As one of the
other observers here (Lisa van Zyl) put it, "it sounds like a very
unhappy star".  Then we saw a few turn-arounds, and received some
beautiful coverage from Stan Walker in New Zealand (10" Meade + ST-6);
the combined data show a well-defined wave from magnitude 13 to 14.5
with a period of about 23 hours.  What a wonderful thing it is to see!

     So now we are trying hard to accumulate long, dense coverage to
study this signal.  The period is so short that one must basically get 
data from several sites around the world.  (Probably the closeness to 
24 hr is a major reason why this periodicity was not previously 
recognized.)  Land masses in the south are rather few, so this is a 
clarion call to Paddy M, Gordon G, and Paul W, as well as Stan W who 
hardly needs it.  Also Thomas - can you help us with this one?  And does 
anyone have e-mail addresses for Chico Jablonski and Raymundo Baptista?  
They would be mighty good allies to have.  The next 11 days are really 
critical since we have scheduled coverage in S Africa or Chile.  The 
theory is that an *unambiguous* cycle count over about 3 weeks and a 
range of longitudes will largely solve the major period-finding issues.  
Later we can rest, smell the flowers, think about what it all means.  
But now we have to work.

     There's a nice V=13.40 star 2.5 arcmin south of V803 Cen, our
favorite comparison.  You can find a chart at our Website
(cbastro.org) or in Astr. and Astrophys. 44, 117
(Elvius 1975).  Sorry, Downes and Shara snubbed this star on account of
its excessive helium.

     I also sent a thing to VSNET asking for help, and there are
perhaps a few more details there (not much though).

     For northerners, I received some LX Ser data from Tonny and
Lasse, and it looked good enough to declare a campaign.  You'll
notice I also did that in the VSNET posting.  AM CVn and EC1533 are
still of high interest, though, esp. for the bigger scopes (Dave E,
Dave W, Cap'n Bob) which can more effectively study these signals of
low amplitude.  We expect to stay with all these stars for the rest of
the observing season.  It's best for you to pick out one or two and
specialize; signal-averaging and splicing methods are more effective
then since calibration difficulties are minimized.

Last night, a spectacular ice storm struck.  Entertaining, but still.
Whatever happened to my plan to avoid winter by sabbaticalizing in S
Africa?

Springboks (local type of gazelle) cavort happily outside the picture
window, oblivious of periodicities and even ice storms.  On the other
hand, they ram each other and lock horns, so I guess they have their
own set of worries.



                        pepe del sur y las nubes