(cba:news) campaign stars in mid-March

[Joe Patterson]

Dear CBAers,

Later today I leave for Kitt Peak, with 13 students in tow (my class). 
This is mostly for general astronomical tourism, though we have an 
observing run and will manage to get some time-series runs.  I suspect 
that I won't have much free time for analysis/writing; let's review 
where things stand now.

SDSS 1339 still deserves plenty of attention; keep going until the waves 
disappear - and then go another week beyond that (since disappearance 
can merely signify beating with a nearby, closely spaced period).  CP 
Puppis is continuing to delight - me, anyway.  The waves are very strong 
on most nights, but power spectra show that there are *at least* two, 
and very likely three, closely spaced signals.  One is Porb - no great 
reward there.  The other(s?) occurs at a frequency I don't recognize - 
and which is possibly afflicted by aliasing since we're having trouble 
getting enough coverage on this star; it's a little late in the 
observing season, and our lack of South American representation really 
hurts us.  Anyway, keep it up for at least another 2 weeks.

ER UMa also shows at least two, and very likely three, signals.  Because 
the star has at three luminosity states (quiescence, max, supermax... 
plus the transitions), we get to study these signals in different 
conditions.  Sort of do a laboratory experiment on these 
likely-precession-related signals.  That's an exciting prospect.  We're
40 days into the campaign, so it's near the end; but I recommend at 
least another 10 days.

It's late for BK Lyn too, but this should be a good star for brighter or 
inferior nights.  Big waves, brighter star.

It's time to come back to AM CVn.  Not as interesting a target as these 
guys who sprout the big periodic waves, but a high scientific impact if 
you're careful with the timing - to probe the long-term period change.
Possibly a good target through the upcoming bright-moon interval.

It's also a good time to get end-of-season runs on the many 
northern-winter DQ Her stars: MU Cam, RX0704+26, BG CMi, PQ Gem, WX Pyx, 
and Swift 0732-13.  We'll pick 'em up again in 5 months, and have an 
absolutely year-to-year cycle count (which most of these stars still lack).

Finally, a couple of runs on YY Sex would be great - especially in I 
light where the signal is very strong.  Just to tune up the ephemeris.

I'll write again from Kitt Peak, after things settle down.  He says, 
optimistically.

joe

p.s. Remember the Boston AAVSO/AAS meeting coming up in May (and you 
need to join the AAVSO to take advantage of their reduced-$$ AAS 
registration fee... and for the AAVSO mtg... and on general principles).