From jop at astro.columbia.edu  Sat Mar 24 23:14:52 2007
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sat, 24 Mar 2007 22:14:52 -0500
Subject: (cba:news) march-april news
Message-ID: <4605E92C.9090809@astro.columbia.edu>

Dear CBAers,

Apologies for my very long silence.  Lots of time needed to take care of 
my 95 yo father in Boston; I've been gone for nearly a month.  I've 
learned a lot about eldercare in the USA - I hope enough to navigate the 
harder problems that may lie ahead.

Plenty of change in the CBA world over such a time.

1. The T Pyx coverage, dominated by Bill Allen, has established the 
     binary phase very accurately; we can now quit for the year.
2. Likewise for DW Cnc, observed by David Boyd, Bruce Dickson, Cindy 
Foote, and Tut Campbell.  And for Swif0732-13, primarily observed by Bob 
Rea.  And WX Pyx, with Bob Rea and Berto Monard leading the way. In 
these cases, *pulsation* phase rather than orbital.
3. Too late in the season for FS Aur, RR Pic, and RX0704+26.
4. HT Cam and BG CMi are still not adequately done.  I strongly 
recommend BG CMi - just two nights would enable us to wrap it up for the 
year.
5. I dunno about U Gem.  Really too late for long runs, and we basically 
need 'em to accurately specify the hot spot's amplitude/phase.  We'll 
have to cover the last part of the cycle next year.

That takes care of basically all the earlier targets.  Onward into the 
(northern) spring...

In the SOUTH, a good target over the next week is DT Oct = RX1840-83, 
presently in superoutburst.  Over the next month, I recommend V382 Vel, 
the remnant of a 1999 nova which flashed some beautiful periodic signals 
three years back.  And RX1039-05 = Sex = (I think) YY Sex, a very likely 
AM Her star presently misclassified (probably).  The latter looks very 
faint, but give it a go - it's very bright in I light, and shows a 2 
magnitude modulation in I light.  Could be a very feasible and 
satisfactory target.  And CR Boo (see below).

In the NORTH, I strongly recommend AM CVn, which is now transiting near 
local midnight and is definitely feasible for all CBAers.  The prime 
need this year is timing of the (somewhat) subtle 17 minute orbital 
signal.  The presence of several more powerful signals at nearby 
frequency means that a couple weeks of long, dense runs are needed. 
Now's the time.  The other long-term target is CR Boo, which is another 
bright AM CVn star chock full of periods, which has not received very 
close attention since the CBA went global.  At 1346+08, it's very well 
placed for all observers, and I hope we can assemble some all-day light 
curves for it.

Finally, there are eclipsers, which need occasional potshots to update 
the binary ephemeris.  AC Cnc, BP Lyn, and UMa6 = H0928+50 all could use 
some attention - one or two eclipses is enough.

So that's it: DT Oct, YY Sex, CR Boo in the south.  AM CVn, CR Boo, BG 
CMi, and the eclipsers in the north.

joe