(cba:news) july stars

Joe Patterson jop at astro.columbia.edu
Thu Jul 20 19:23:17 EDT 2006

Dear CBAers,

Olde Whiteface is out of the way again, and it's been a while. Let's
discuss targets.

Time to drop some stars.  V1316 Cyg had a great and well-covered outburst,
and the coverage has been excellent.  But it's (long since) over, and
David Boyd is writing up the results.

We have a 40-day baseline on V617 Sgr.  Great star!  But that's enough to
wrap it up for the year.  A short but sweet ephemeris/classification paper
would be timely.  Anyone want to take a crack at the data?

V1223 Sgr. Similar story.  Pretty good coverage, mainly from Berto, Bob
Rea, Chris Middleton, and Bruce Dickson.  The main periodic signals show
up nicely.  But it's time to demote it as a major (coordinated) target -
but retain as a target for just a few more observations this season (say
till October).

V603 Aql. Good, dense coverage from Tonny, Bart Staels, Pierre de Ponthiere,
Bob Koff, and Cindy Foote.  This will track the positive superhump pretty
well.  But time to move off to other stars.

NEW (more or less) stars.
V419 Lyr jumped into superoutburst a few days ago, and David Boyd has
found superhumps.  We need to track these - previous data leaves cycle
count uncertain, so the star is still in the realm of "poorly studied".
At 15th mag and with healthy superhumps - and well placed - it's a
tempting target!

RX1730-05 ("Oph").  Nice 16th mag star, with some nice periods - and some
we haven't yet established, I think.  But you HAVE to keep the integration
cycle short, no more than 40 s. This is because the star has a very rapid
period - just 128 s.

And along those lines, it's time to start a season's timings of DQ Herculis,
which has a 71 s period - and hence needs a total integration cycle
(integration plus dead time).  Good challenge for data quality!

RX1803+40 ("Her") is new to CBA menus.  It's a newly discovered DQ Her
star, with a long spin period.  It's 18th mag, which normally disqualifies
a star for CBA action.  However, with a large pulse fraction and long spin
period, I think it's feasible.  We'd like to track the phase over the rest
of the season; if we don't no one else will!  A good target for a quality
night in the dark of the Moon.

V1494 Aql was that very bright nova in the fall of 1999.  Since then we've
kept close watch on it, and the star has rewarded us with an orbital waveform
which changes every year, as the white dwarf cools after outnurst.  We
missed last year, though - and should make a great effort to find the new
orbital waveform.  Orbital waveforms after outburst act like a bolometer for
the white dwarf temperature (because they arise from a reflection effect),
and that temperature isn't really accessible in any other way.  Unfortunately,
I don't know how bright V1494 Aql is now - can someone find out?  Assuming
it's not too faint, the idea is for repeated light curves around the 3.2
hour cycle.

CI Aql has a very similar story, though has a long period (14.5 hrs). Same
idea - find the waveform and time the eclipses.

Finally, FO Aqr and AO Psc (especially the latter) remain good targets for
short observations - since they have relatively fast periods and high
amplitudes, and they're 13th magnitude.

Whew, that was a big menu!  For southerners, I recommend:

V1494 Aql
CI Aql
Pulsators (esp AO Psc)

For northerners, I recommend trying RX1803+40 but only a few of you are
likely to get that faint.  If you can't, I recommend V419 Lyr, DQ Her, CI
Aql, and V1494 Aql.


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