March stars

From: Joe Patterson <*jop_at_astro.columbia.edu*> Date: Thu, 04 Mar 2010 18:41:02 -0500 · jop_at_astro.columbia.edu

Dear CBAers,

  What a great campaign you're all doing on U Sco!  I'm not part of the fun
myself (we just forward the data to Brad, who analyzes it more expertly
and quickly than I could).  But I've certainly adnired the result.  I
didn't think it possible for Scorpius in February.

  I wonder if I could draw your attention somewhat away from U Sco 
(and since it's fading fast, maybe this is timely).  There's a spate of
DQ Her stars (intermediate polars) in the March evening sky, and we're
trying to track the periods of their rapid optical pulses.  Ideally one
wants pulse timings early and late in the observing season, to give a
baseline sufficiently long to count cycles from year to year.  (You don't
have to do this every year, but you definitely need it occasionally - since
the period changes.)  We got a decent collection of pulse timings a few
months ago; let's reprise 'em now!

Here's the collection of stars:

RX0704+26 = Gem (paper ready to go on this one - just need 2-3 March timings)
RX0636+35 = Aur
V405 Aur
PQ Gem (V filter - not clear)
MU Cam
Swift 0732-13

As for stars in the current program, Little Swifty is a dud (or perhaps is
just too faint for us).  Off with his head.  I'll finish with the Big
Swifty analysis in another day or two.  (Doesn't look good, though.)

It's DEFINITELY time to start up the AM CVn program!  A prime object in
the March and April sky.  The light curve is no crowd-pleaser... if you
can see the variability in the raw light curve, your data's pretty good.
But in that ever-so-modest light curve lurks some fascinating periodic
signals - in particular the orbital period, whose long-term change may
signify the rate of gravitational-wave radiation.

The other CV we'd like to wrap up is UMa 6 - a strange 10-hour eclipsing
binary that's been hanging around unpublished for about a thousand years
(hence its failure to get a decent variable-star name; the Russians don't
assign a name until an official publication comes out).

Now for a dwarf nova which has intrigued me.  I'm likely too slow on
the draw here - it was bright a couple of weeks ago.  But it's likely
to be quite a fascinating star; can someone look and see if it's bright
enough for time series?  It's CSS 100217:104411+211307.

     Finally, can you guys let me, and Jerry Foote, know if you're
planning to attend the SAS (Big Bear, CA) meeting in May?  The SAS
meeting is big enough that they need plenty of advance notice to
schedule the talks... and you'll also want to reserve soon to guarantee
housing.  Thanks!

joe