(cba:news) stars for mid-november
jop at astro.columbia.edu
Mon Nov 11 17:50:26 EST 2002
Time to report on the main two campaign stars of the moment, VY Scl and
V592 Cas. Both have been covered very well.
V592 Cas has basically lost its superhumps. The humps we found in 98
were fairly lame to begin with, and now they've dropped below detection
limits. Impressively bashful. It does have the side benefit that without
this signal, the detection of higher-frequency signals ("QPOs") becomes
clearer. And in particular, we have a very high-quality power spectrum
(averaged over 30 nights) showing a broad signal near 95 cycles/day.
But it's reason to quit. Away with it!
VY Scl is weirder. It's very well covered by Berto, Jonathan, Bob Rea,
Neil Butterworth, and Greg Bolt... pretty much round-the-world coverage.
There are signals near 1 c/d, but they have lousy stability... and with
poor stability and an unfortunate choice of frequency, the matter becomes
very difficult to prove. We have a good orbital ephemeris, QPOs at 50
c/day, and some suspicions of negative superhumps. But as the data set
gets better, the results don't get clearer... not a happy circumstance.
Since we can't do better than global coverage, I think we should retire VY
Scl for the season (unless it dives into a low state!)
The southern star of the night should be EC05287-5857. Very nice
collection of periodic signals in this fella, and they appear at first
glance to be stable. Let's try for that horizon to horizon!
The best northern campaign star is Tau 2 (KUV 0358+0614), and I hope I can
convince some southerners to observe it also. I believe it will be a
great winner also, available to all hemispheres and practically all night
Finally, for small northern scopes and moonlit skies, a campaign on BZ Cam
is right around the corner. Be the first on your block to get the new
season's light curve.
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