(cba:news) March stars

Joe Patterson jop at astro.columbia.edu
Sun Feb 29 12:03:55 EST 2004

Dear CBAers,

Sorry for the long silence.  I'm now teaching simultaneously at Columbia
and Princeton, and it's kind of wearing me out.  Thank heaven for spring
break in 2 weeks.

I did manage to finish the DW Cnc paper, and expect to send the final
version off tomorrow.  That's with co-authors Vanmunster, Martin,
Campbell, Robertson, Kemp, Messier - I hope I didn't forget anyone!  Great
star, with three very tractable periods (white-dwarf spin, orbit, and the
frequency difference between them).

We didn't seem to do very well this month with eruptive objects.  For
ASAS 1536-08 I haven't finished analyzing the data, but it's hampered by
the bad sky position.  No one can get long runs on equatorial stars
out-of-season, so we just have brief snippets of data - very unfavorable
for period analysis.  Time to take that off the menu, I guess.  BZ UMa
just erupted, and that mysterious star deserves a *lot* more study.
Vanmunster and Starkey got good data sets... but it looks like the
eruption is short, possibly already over (?).  It could still pan out, but
it's kinda doubtful right now.  U Gem just erupted, and this is a good
target for the bright of the Moon coming up.  We'd like to get orbital
light curves for the whole eruption cycle - and we might as well start
now.  But you will need to cover most or all of the 4.2 hr orbit; short
runs aren't of much use now.  (Also, you'll have a nearby Moon for the
next coupla days.)

Methinks the best northern target now is SDSS 0809+38 ("Lyn" in CVcat).
This star has a 2.4 hour spectroscopic period, but our data - from Cook,
Martin, Krajci, Messier - suggests a 3.2 hour photometric signal.  This is
not a certain result, but it's strong enough to elevate the star's
priority.  Let's chase that star down into a tree on your northwest

The other good northern targets are RX0625+73 ("Cam") - good for very long
runs, good to fight off that Moon rampaging through the ecliptic - and BH
Lyn.  BH Lyn is a star in which we found superhumps in 1997, but with
one-day aliasing preventing us from assigning + or - status to it.  That
can be fixed with good geographic distribution.

In the south, the T Pyx campaign can be suspended for a few months. We
have a very good timing from the last week (Monard, Rea, Allen), and it
fits in with the violently-increasing-Porb ephemeris.  Consider trying WX
Pyx.  At V=17.7, this star ain't right for just anyone... but its
pulsation signal is quite large, within reach of a 10-inch in white light.
It would be great to follow the 26 minute pulse through two observing
seasons, establishing a long-term ephemeris.  Good dark nights only,

Then there are the Hydra boys.  There's a weird cluster of CVs in Hydra
found by the Edinburgh-Cape survey.  I recommend V393 Hya = EC10578-2935.
It has a nice orbital (or possibly superhump) signal, and a pretty QPO
also at ~16 minute.  Very nice for studying the QPO phenomenon.

I'm also going to keep AH Men and EX Hya on the menu.  These are really
always excellent targets... good for brightness, length of observing
season, and astrophysical rewards.

Delete FS Aur, BG CMi, V436 Car.

Nice planetary lineup in the evening sky, hey?  Sure is good for star


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