(cba:news) victory over AM CVn, now for sdss1238...

[Joe Patterson]

Dear CBAers,

We've finished 45 nights of AM CVn coverage, and today I caught up with
all the analysis and derived new ephemerides.  The orbital (1028 s)
variation is always hard to spot, and this year all the more, because the
negative superhump (1011 s) was strong.  But with enough coverage, which
we got, one can still extract the weaker signals in the presence of strong
ones.  So we emerged with three timings of minimum light, all agreeing
within 0.02 cycles (20 s).  Comparing with the long term ephemeris, it's
now clear that the period is slowly decreasing over the available 28 year
baseline.

So we can retire AM CVn for the year.  But I'm still lusting after
SDSS1238-03!  This is 17th magnitude and I realize not a real fun object
for CBAers... but is a terribly important star and shows a strong maximum
about every 7 hours.  Under good conditions this should be accessible to
apertures of 25 cm and above - and with its nice equatorial position, we
ought to be able to get worldwide coverage.

I'll write later on brighter stars!

joe