(cba:news) dq her pulse maintenance

Joe Patterson jop at astro.columbia.edu
Sun Apr 3 09:35:02 EDT 2011

DEar CBAers,

The ER UMa campaign is going very, very well: 70 nights of nearly 
continuous data!  But as it gets better and better, the *percentage* 
improvement of coverage gets less and less.  The main goal - 
understanding how the negative superhump interacts with the various 
normal and super-outbursts - is likely to be significantly enhanced by 
more coverage.  So *some* coverage of the star, especially near 
quiescence at V=15, is still quite desirable.  But I'm inclined to pull 
the plug on it now as a major campaign target.

Likewise for SDSS1339+48.  The super-outburst is long over, and, as is 
typical of these WZ Sge stars, the superhump lingers for a long time - 
like a headache after you bump your head.  I'd say the law of 
diminishing returns has knocked this star off our menu.  The star at 
quiescence has white-dwarf (rapid) pulsations, so at some point we want 
to revisit to see if they have returned.  But that's mainly a project 
for 2012, not now.  Sayonara.

Finally, YZ Cnc.  Another long and successful campaign, with coverage in 
quiescence, normal outburst, and superoutburst... and 2 months long.
I'd be inclined to end this campaign also.  However, Arek Olech will be 
writing this one up, so I'll give him the chance to register an opinion 
on this.

Unless another glamor star fires up, we've got an opportunity to do some 
serious maintenance work on the ephemerides of DQ Her pulses. 
Time-series photometry early and late in the observing season is always 
of extra value since it constrains the cycle count in the typically 
8-month gap between seasons.  And (northern) spring is ideal since it 
can service the two main clusters of DQ Hers: in the winter and summer 
skies.  Sorry for the long list, but here are evening stars who can 
really use the attention:

HT Cam, RX0636+35, RX0704+26, Swift0732-13, WX Pyx, DW Cnc (long run 
only), PQ Gem, MU Cam.  Vaguely in order of declining priority, but 
really, it's not possible to predict which stars will have high 
potential for high-impact observations, since it depends on the rate of 
period change - which is unknown, and is the point of observing them!
Unlike our usual observing philosophy, these stars don't need 
particularly long runs (3 hrs is plenty), and you can do a menagerie of 
stars without concern about diluting your efforts.

And here are morning stars, with same comments applying: DQ Her (maximum 
20 s cycle time), NY Lup, RX1654-19, V4743 Sgr, RX1730-05, and V1223 Sgr.

And two middle-of-night guys: EX Hya and YY Dra.  The latter would 
probably repay observation in *blue* light - and probably would need 
quite long nightly observations (there's an M dwarf which is annoyingly 
strong in the spectrum, and needs to be subdued.

Finally, there's AM CVn and HP Lib.  Very, very good targets, in the 
prime of their seasons... and if you like the all-night targets, these 
are the stars for you!


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