(cba:news) Stars for May

[Joe Patterson]

Dear CBAers,

Time to replace the actors!

The AM CVn campaign is ready to end.  The 1028 s (orbital) is now
well-timed for April-May, which stretches the baseline out to 14 years -
and basically means that we don't need to visit the star for orbital
period timings for another 5 years or so.  There's another reason to keep
going - the 1011 s signal which is flexing its muscles - but on balance I
think it's time to say finis.

The two good northern objects now are RX1643+34 (I dunno a proper name for
it yet, but it's "Her" in CVCat) and V380 Oph.  The former star was the
subject of a great 2002 campaign (published in PASP) but needs another
crack, to study the QPOs which were such a salient feature.  It's about
12.7, very good for doing battle with the Moon.  V380 Oph is fainter,
about 14.6, with a Pspec but not much else known about it.  It seems to
have some sort of photometric wave of decent amplitude - in a few weeks
we'll figger out what it is!

I'm inclined to end V803 Cen too, with some trepidation.  We've been going
40 days now, and for most of that time it's been in the "cycling state"
with about a 23-hour quasiperiod.  Excursions to the low or high state
would be of great interest, and we can't be sure of catching 'em properly
unless we keep looking... but meanwhile there are other fish to fry.  I
recommend switching off V803 Cen, except to check the brightness; if it
jumps to 13.0 or 17.0, then it's time to jump back into action.  I
recommend replacing it with V2400 Oph - a moderately bright (14.7 or so)
intermediate polar which has been very reticent in yielding its periods.
With coverage in South Africa, New Zealand, Australia, and potentially
Argentina (Paul Warhurst) we might finally crack this tough nut!

joe