(cba:news) Stars of the Equinox

Joe Patterson jop at astro.columbia.edu
Sun Mar 9 14:05:36 EST 2003

Dear CBAers,

Orion still rides high in the evening sky, the snow is still on the
ground, and Olde Whiteface is gearing up for yet another assault on the
night.... But the temperature threatened 50 yesterday, the PGA moved back
East, George Steinbrenner has failed to destroy baseball for yet
another week, and spring break is a week away!  So things are lookin' up.

Time for a major overhaul of CBA targets.  Both UMa7 and HQ Mon have
yielded some fairly disappointing light curves, not things you want to
show your mom.  But a power spectrum indicates that UMa7 is actually
delivering the goods, showing multiple periods.  Part of the reason
for the ugly light curves is the beating of incommensurate frequencies
with similar amplitudes.  This is the work of Tonny, David Messier,
Jerry Foote, and Brian Martin.  Tonny will announce the result when he's
ready... but for now the important thing is to vault UMa7 up there as the
top target for northern observers.  With that lovely location (1004+66)
and adequately bright (about 15.2), it should survive the onslaught of
moonlight pretty well.

10 04 34.69  +66 29 14.6 (2000), for the record.  The best comp appears to
be GSC 4143:823, if it's convenient to get it on the chip.  We can live
with other comps, though, if you document things pretty well.

HQ Mon is different.  Not yet suitable for either your mom *or* the
astronomical journals (whose standards are obviously lower).  Lew Cook,
Robert Rea, and Tom Krajci have been pounding away on it.  But with HQ's
equatorial location and (slightly) unfavorable season, the individual runs
have been not as long as we'd like, and the star's period turns out to be
near 8 hours - a tough one for us!  Plus the star waffles around with
a ~0.5 mag variation on a timescale of a few days, which seems to
disturb the amplitude of the faster signal.  Very tough.  Just for the
(informal) record, the photometric signal is likely to be at 7.59+-0.08
hours - but I'd hate to have to prove it!  So we'll RETIRE HQ Mon until a
future observing season.

So the Q-Mon boys, HQ and KQ, have survived CBA attack for yet another

The prime SOUTHERN target should now be EC11588-3142 ("Hya" in the CV
Catalogue).  The first looks by Lew and Bob Rea (and Berto) are
exceptionally promising. It's bright enough (13) to survive moonlight and
well placed in the sky.  We need LONG runs to decipher its timescales of
variation.  First indication is something like (~15 minute flickering, ~4
hr signal, maybe ~4 day signal)... kind of CBA blue-plate special for a
long campaign.  I hope that observers in the southern USA will consider
this one too - even a 2-hour run might bridge the gap between the southern
observers and thereby give us our round-the-world calibration (we still
have no one in South America).

12 01 24.35   -31 59 26.8 (2000) for the record.  GSC 7235:1420 and
7235:1435 are both very acceptable comps.

So those are the big ones.  Here are the others:

SOUTHERN.  T Pyx: we need one more set of orbital light curves (about a
week's worth).  That'll nail down the orbital phase to high precision
until next year.  (Unless it erupts, of course.)

WX Cen.  A probable supersoft, quite bright and crying out for another CBA

NORTHERN.  EC11588-3142: well, I hope you can do it.  However, I hear you
can't get blood from a turnip.

V405 Aur and PQ Gem: DQ Her stars in need of late-season pulse timings.
Perfect for a few hours in the evening.

FS Aur: a mystery star, out of season but we're trying to phase up its
strange 3.5 hour variation over the past 5 years.  Off-season timings are
of particular value in that enterprise - but they do have to be ~3 hrs

Well, that's the menu.  See what tasty things you can find in it!


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