(cba:news) The seasons, they go round and round
jop at astro.columbia.edu
Thu Nov 30 09:57:42 EST 2000
Time for a fresh update on targets.
The main northern target has been PX And. We've had good coverage and
seen the customary negative superhump, though decidedly weaker than in
1996-1997. Time to bring this campaign to an end. The best long-night
target to replace it is WX Ari, just about the only superhump holdout
among the SW Sex stars. It's a great time of year for long coverage,
and I hope we can get some AU/NZ coverage too - at a dec of +10 it
shouldn't be too exotic for those folks. Chart on the CBA website.
Two major developments down south.
Fred and Jennie have been firing away at BW Scl. They haven't had the
best of weather and the star's a bit faint, but their coverage is easily
good enough to extend the binary ephemeris (indefinitely). So that's
reward number one. But lo and behold, another signal popped up, a very
big one... a signal at Porb+16%. We don't know yet what this is, but you
southerners can still follow this thing - so I sure hope you do! Next
year we'll mount a major campaign from several sites - but this is a
*transient* phenomenon (lasts maybe a few weeks to a few months), so
it won't always be there. It's very late in the observing season, but see
what you can do!
By the way, this signal was found earlier by Tim Abbott. You can see it
in Astr and Ap, 318, 137 (Figure 8). But he thought it might be due to
aliasing. It's not - it's quite far displaced from the putative Porb.
Similar excellent news re RR Pic. I've spent the last few days studying
these light curves. As Vogt, Warner, etc. previously found, the light
curve changes shape but maintains a basic periodicity of 0.14502 days.
Our data suggest that the changes are themselves cyclic with a period near
2.0 days. One of the 10-day segments shows an obvious negative superhump
at omega-orb + 0.48 c/day, plus a strong signal at 0.48 c/day. Happily,
RR Pic season is just getting started, so I warmly recommend this fine
star for your summer enjoyment down there! And I'll be happy to send all
the data to any fine deserving southerner.
Finally, here's my usual request for DQ Her star observations: FO Aqr, AO
Psc, V709 Cas, BG CMi (especially), V405 Aur. Very nice targets for
quickies. Mind your clocks. 1-900-410-TIME just to be sure.
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