stars for the solstice

From: Joe Patterson <*jop_at_astro.columbia.edu*> Date: Sun, 20 Jun 2010 00:01:56 -0400 · jop_at_astro.columbia.edu

Dear CBAers,

   The response to RX1654-19 has been just great - from pretty much
everyone.  Thanks to that and those time-series-friendly southern winters,
we've accumulated the best set of data I could possibly have hoped for.
We have a long string now of nearly 24-hour light curves, and that has
revealed the basic frequency structure: 6.463 c/d for w_orb, 158.053 c/d
for w_spin, and 151.588 c/d for the the sideband (sometimes called "beat").
Pretty much plain vanilla intermediate polar.  Aside from another pulse
timing in late season to slightly refine the exact frequencies, we'll never
do any better than this!  That means it's time to quit.

   As it did in 2008, GW Lib is sprouting a strong 4-hour signal in its
light curve - compared to the 2-hour signal exhibited prior to the 2007
eruption.  The origin of this signal remains unknown.  It appears not to
be stable in phase - that's never a good sign (if true, it means that
more observation will not improve knowledge of the period).  And the
pulsations, quite strong in 2008, are so far not evident.  GW Lib is a
good target for two more nights (I think), then probably not for four,
due to unwanted visits from the Moon.  Then we'll see if it warrants
continuing further.

   As you all know, a new dwarf nova popped up in May: OT2138+36, in
Pegasus.  All northern CBAers have been following it; it's still humping
and well worth following for as long as possible - which might be forever
(it gets 4 minutes easier every day).  Tom Krajci has found one of the new
Catalina Sky Survey CVs (CSS100615:215815+094709) superhumping along last
night; let's keep up the coverage!  That's OT2158+09 in our lingo, and
you can find all details at
http://nessi.cacr.caltech.edu/catalina/AllCV.html.
That's the site for all the CSS CVs, and a second CV was discovered on
the same day (CSS100615:222824+134944).  This one might be too faint by
now, but the magnitude range of 6.9 mag makes it awfully interesting.
Both of these guys would greatly reward attention.

   Bob Rea has successfully obtained some V4743 Sgr data, so that one
is back on our radar screens.  We just need a few more good long runs
to complete our 5-year study.

   Now for the *bright* stars.  We need them to survive this coming
week's moonlight.  I recommend V699 ph (now in eruption) and V841
Oph (a bright nova remenant that we have somehow never studied), and
WX Cen earlier in the evening.  In the north I recommend V795 Her as
a good all-night target - we haven't studied it for about 10 years,
and have a much better network now.

Lots of choices - good luck navigating them.  Happy observing!

joe

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