(cba:news) January stars

Joe Patterson jop at astro.columbia.edu
Sun Jan 3 09:21:20 EST 2010

Dear CBAers,

Now that the Moon is safely (well, mostly) out of the way, here's a 
recommended menu for the next couple of weeks.

First the north.  Nights are long, and I really hope that the Euros will 
find some clear weather to extend our daily baseline on these guys.  The 
star I'd like to promote most heavily is RX0704+26 ("Gem" in the Downes 
catalogue).  This is a 480 s variable with  practically all the power at 
240 s, so the cycle time needs to be short - really no more than 60 s. 
At V=16.5, that might seem ambitious - but this star has a really, 
really large amplitude... and the observing issue is practically always 
time resolution, not signal-to-noise.  I promise you - the light curve 
is gorgeous with good time resolution, and looks like a mess (though it 
isn't quite) if you don't resolve the pulse.  (It turns out that the 
timing information is still decent if you don't... but better if you 
do.)  With that RA and Dec, it's suitable for all-night coverage, and 
that would be scientifically very desirable as well.  It's surprising 
that light curve evidence for Porb still eludes us - and I think it's 
because we still haven't had a concerted campaign.  This is a DQ Her 
star (intermediate polar); we know the star's basic specs, but it cries 
out for a strong campaign - and now's the time.

Early on in the night, XSS0056+45 is still a great choice.  The spectrum 
of pulsations in this star (another DQ) is quite complex, and it'll 
probably require a multi-longitude campaign to resolve it with 
certainty.  Same goes for a long period (something around 0.5-2.0 days, 
which the star seems to possess, but which is hard to study from one 

Finally, AM CVn.  Still quite early in the observing season, but we do 
need early-season timings to complement the dense March-April data I 
hope for.

Plus the various DQs for which short observations (2-3 hours) would be 
fine:  RX0636+35 = Aur, V405 Aur, MU Cam, HT Cam (kinda faint), DW Cnc.

In the south, two stars for sure: WX Pyx, for which the earliest 
observations - mainly from Bob Rea - are showing a very high pulse 
amplitude this year.  Great for most-of-the-night coverage.  And T Pyx; 
I have that paper ready to go, but now that January has rolled around, 
I'd love to squeeze in one more observing season.  Just a couple weeks 
would do the trick, since the cycle count issues are solved.

Finally, YY Sex, preferably through an R or I filter (the amplitude is 
really high in the I band).  A little early in the season, but should be 

I'm leaving for a meeting this morning, so will have somewhat crippled 
email access for a week.  But I think I'll still be able to read it. 
Happy observing!


the night, AM CVn is.  That's the main troika I want to promote for
northern observers.  I'll cobble this together, add southern targets,
and send out later today.


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