(cba:news) CR Boo and April stars

Joe Patterson jop at astro.columbia.edu
Tue Apr 1 08:31:11 EDT 2008

Dear CBAers,

Sorry for the long silence.  I have, however, been busily analyzing 
data, and it's time for a new slate of target stars.  BTW was anyone 
else scammed by this morning's April Fools' joke about the new NASA 
program?  I thought it was pretty good... but it coulda been even more 
outrageous (and I still would have bit).

I've fully analyzed the season's AM CVn data, and all of it yields a 
consistent phase and waveform for the weak 1028 s orbital signal - which 
was our objective.  Strangely, the dominant signal this year was at 1051 
s, which is normally very, very tiny compared to its first harmonic at 
525 s.  I dunno, and neither does anyone else, what the significance of 
that is.  Anyway, it was impressive coverage, and we got enough.  In 
fact we even can now connect all 30 years of orbital timings in one 
grand ephemeris.  I consider that a great accomplishment!

So AM CVn should be swept off the stage.  Likewise for YY Sex = 
RX1039-05, thanks mainly to the great efforts of Robert Rea.  We've been 
tracking that one for six years, and have a fine constant-period 

OT0559-51, HV Vir, and CSS080304 should also be swept away.  We did 
pretty well with the second and third... but more important, the 
outbursts appear to be over.  The secondary targets are mostly DQ Her 
stars, and all in the evening sky.  We have *some* coverage for each, 
but would profit somewhat by 2-hour runs now quite late in their 
observing seasons (very late and very early in the season means short 
observations, but greater leverage over the long-term cycle count).  But 
two *other* DQ Hers are in this category, not on the present list, and 
deserve even greater emphasis: WX Pyx and HT Cam.  Both are 17th mag 
stars but have fairly prominent DQ Her signals... we're in the dark of 
the Moon, and a good night will yield a pulse timing!  So those are good 

CR Boo just jumped into superoutburst, and at 1346+08 it's very well 
placed for long observation at all longitudes and latitudes.  We haven't 
extensively studied it for 12 years, and it's really ideal for today's 
CBA.  So I heartily commend it as a great target for the next few weeks.

And it's EX Hya season again.  Perfect star for you Australites on 
lower-quality nights.  Time to tweak up that long-term ephemeris.

CI UMa is a northern dwarf nova we've never quite studied, and that just 
went into superoutburst.  Perhaps well placed for some northern CBAers, 
depending on observatory/telescope details.  I'd love to see some data 
on it.... But I do recommend CR Boo with greatest emphasis, because we 
have a good chance of accumulating data from many longitudes.

Happy observing!


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