(cba:news) stars for july-aug
jop at astro.columbia.edu
Tue Jul 26 09:16:56 EDT 2011
Sorry for my long silence. While on vacation I had some minor injuries
falling on the rocks in Maine (arms, hands, fingers - made typing a tad
difficult). You don't notice the cold of the water so much when you're
dumped unceremoniously into it. But it was otherwise a fine vacation!
CBA data has also slowed, partly due to the summer monsoon in the
southwest USA, except for Berto and Tut Campbell/George Roberts, who are
unstoppable. We are still trying to track V1432 Aql, a fine target with
lots of action and an eclipse. It's an "asynchronous polar", with Prot
and Porb slightly difference - and with the difference (allegedly)
slightly decreasing with time. This process of "relocking" magnetic
white dwarfs is a fascinating piece of physics, which it's up to
observers to constrain. That would be us. Unlike most of our targets,
there's no great advantage in every-night coverage. Occasional visits
spread out over the observing season are fine. The beat period is 50
days, so every 5th day gives good definition of this cycle... and we'd
like to get 2 cycles (100 d) during a season.
V1432 Aql was once a mega-celebrity object, thought to be the only AGN
with a strict period. Then a CV was found right next to the AGN; the
AGN was greatly demoted in status, but the newly-discovered CV became a
minor celebrity in its own right, because it joined a really tiny class
of CVs, and became instantly the best-observed such object (partly
because of all the prior data taken under the AGN banner).
V1974 Cyg, was an even greater celebrity, called "the nova of the
century" (1992). I think it probably deserves this title, though it's a
touch unfair since soft X-ray and infrared detectors didn't get a peek
at the great novae of yesteryear. Anyway, it's still hanging in there
around 16th magnitude, flashing definite superhumps. This is a somewhat
challenging star (faint, crowded field), but still accessible to many
CBA scopes. Great target if you're up for something hard (good sky and
telescope conditions needed).
The other two old novae we're trying to put to bed for the year (and
finish papers on) are V1494 Aql and V4743 Sgr. Also around 16th mag,
and both with strict - well, probably strict - periodic variations.
Along with V1974, each of these stars would reward *intense* study -
long observations spaced over consecutive (as close as possible) nights.
As usual, I'm hungry for time series of DQ Her stars. V1223 Sgr is an
easy target but has been neglected this for the past 2-3 years. V2069
Cyg needs some help, as does RX2133+51 and V2306 Cyg. All highly
seasonal. In the morning sky, IGR0023+61 and V709 Cas (tough target,
low pulse amplitude). These targets are basically suitable for
once-every-few-nights, though would somewhat profit from one denser data
Finally, there's V455 And - the star that never fails to delight (but
also never relaxes enough that you feel it's time to write the paper).
Can you possibly get 15 s time resolution on this 16th mag star? If you
can, I'd be eternally grateful! (For the data, not just that you could
Enrique de Miguel is spending the summer with me in NYC, and Jeremy
Shears is visiting both of us next week. Good opportunity to connect
with far-flung CBAers, even without leaving home!
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