(cba:news) stars for july-august (Joe Patterson) [2009-07-28T14:42:33Z]

Dear CBAers,

     Time for some wholesale changes up there.  The major target over the
last month has been V4743 Sgr (Nova 2002).  Intensive coverage by Berto
and Bob Rea has established the 2009 light curve with exquisite
sensitivity; there are two periods in the light curve, both absolutely
stable - at 1419 s and 6.7 hours.  We have five-year ephemerides for
both.  So it's time to end the campaign - EXCEPT for a few end-of-season
time series in September, which will broaden the baseline and clinch
the long-term cycle count beyond any doubt (admittedly, there's still a
smidgen of doubt).

     V442 Oph has been more disappointing.  This is the first significant
photometry at minimum... but it's not a very deep minimum (about 16.9),
and in particular the spectrum is more like a typical dwarf-nova low
state, according to John Thorstensen.  More important for us, the
periodicity content of the light curve is meager; Porb shows up (that's
nice), but nothing else significant - just a whole lotta flickering.
So it's time to end the campaign.

     On the "white-dwarf pulsar" program, there has been good early-season
coverage of AO Psc and FO Aqr - so these guys can be stashed away until
late in their seasons (Nov-Dec).  Other July-Aug stars on the program,
but not receiving coverage, are: V1223 Sgr, RX1803+40 = Her, RX1730-05 =
Oph, and IGR0023+61 = RX0022+61 = Cas (this star is likely to be near
mag 15, not 18 as Downes has it).  Let's get some nights of coverage on
these stars.
    
     It's a good time of year for SDSS2100+00 (= Aqr in Downes catalog),
which has been on our lists for some time, due to "permanent superhumps"
which were reported a few years ago.  I didn't think that was really
proved in the published paper, but the light curves do look very
interesting... and the star has freshly erupted!  It's at 15.5 now -
get thee to a telescope while it stays reasonably bright.
    
     David Boyd has found superhumps in SDSS1610+09.  Not a good time of
year for this star, but we can certainly decode the period structure if
we can get round-the-world coverage.  At a dec of +9, we can do that!
            
     An interesting, freshly erupted, southern star is OT223003.0-145835,
which Gianluca Masi has apparently just found 1.5 hr superhumps in.  Another
good and timely target.

     Finally, there's WZ Sge.  Somehow we've never done a campaign on it
at quiescence.  Considering its celebrity, it's high time to rememdy that
oversight!  Now transiting near local midnight, it's a very fetching
target up there in the sky.  Let's start the season's campaign!


   joe