(cba:news) january targets

Joe Patterson jop at astro.columbia.edu
Thu Jan 15 21:50:08 EST 2009

Dear CBAers,

Sorry for letting the current targets get a little brown around the 
edges!  I've been taking advantage of the Xmas break to write up papers, 
and have been keeping up with the data you've sent.  But the eruptions 
have faded, the year has turned, and... time for a new menu.

    Dwarf nova eruptions are by their nature unpredictable, and the most 
interesting ones are faint and mighty rare.  So these are, at least for 
now, in abeyance.  Every January, though, a host of DQ Her stars rolls 
around in a good sky position.  We haven't seen any of 'em in 8 or more 
months, so they're all ripe for sharpening the period measurement 
(through lengthening the baseline).  *Both* periods - rotational and 
orbital... with an outside chance of another one (superhump or some such 
thing) jumping up and saying hello.

    The fairly easy stars to do (no great challenges in terms of 
brightness) are:
IGR0023+61 = RX0022+61
V405 Aur (0558+53)
RX0625+73 = MU Cam
RX0636+35 = "Aur"
BG CMi (0729+103)

The slightly harder stars to do are:
RX0704+26 = Gem
DW Cnc (0758+16)

Now our usual strategy for practically all stars is to stay on one 
target all night long (or substantially all night).  That always gives 
the best chance of finding something altogether new.  And in this case 
that might be true too - adopt a star and stay on it for two weeks!  But 
strictly for the purpose of accumulating pulse timings - and thereby 
tracing out the long-term period change, it's better to knock these 
stars off in little 3-hour segments, jumping around the sky from star to 
star.  Then it might be feasible to track most or all of the targets.
Take yer pick!

There are a few exceptions to this call for a long assault on the DQ Hers.

1. T Pyx. I'm just finishing a paper on the 1998-2008 timings.  It would 
be nice, and easy, to fold in the 2009 timings.  About 2 weeks of solid 
observation will no the trick.

2. V436 Car. This continues to haunt me.  We've had one decent campaign, 
but never a really good one.  The star has a very, very high proper 
motion , suggesting it's very nearby.  But we still just haven't figured 
out the periods.  Perfectly timed!

3. AM CVn.  Same comment as T Pyx.  But unlike T Pyx, it's still just a 
touch early in the observing season.

And lots of CBA correspondence to catch up on. That's what tomorrow is for!


More information about the cba-public mailing list