(cba:news) august stars
jop at astro.columbia.edu
Wed Aug 15 09:54:31 EDT 2007
Many apologies for my long silence. It has been an arduous summer,
mostly from my father's long illness and eventual death. The head is
starting to clear now, and I look forward to getting back to minding the
Several campaigns have reached successful conclusions. I've succeeded
in tying down all 25 years of V1223 Sgr timings with a simple
constant-Pdot ephemeris, and that means we can leave this star alone for
at least a few years... and publish the result simply and promptly.
Likewise, we've covered V1494 Aql during the last five years, and have
excellently covered the change in orbital waveform (which changes
year-to-year, but no faster). That's another one scheduled for rapid
and simple publication.
It's also time to end the V533 Her campaign. That one is still puzzling
me... but it needs to step aside for bigger fish to fry.
In the north, there are now two dwarf novae urgently needing a
time-series photometry campaign. V1006 Cyg and MN Dra. Both appear to
have orbital periods roughly in the period gap, and superhump
measurements will nicely test our understanding of what happens in this
Porb region, which is still so dimly understood. Pick one and observe
it for a few weeks! MN Dra gets very faint in quiescence, but we'll try
to pick up any slack with large-scope data if needed. V1006 Cyg you
might be able to track all the way to quiescence.
The third important northern star now is RX1803+40, a little-studied DQ
Her star. Good backup for the two erupters. A second-priority backup
is V Sge, whixh is a good target for poor nights, since at 11.5 it's
No major erupters in the south right now. The V1432 Aql campaign is
worth continuing; we want to measure the synchronization rate of this
"asynchronous AM Her". In principle we need ~50 days to make the
measurement - the beat between Porb and Prot. In practice, probably ~35
d will suffice to pin down the phase.
I recommend two new stars in Indus. EC2117-54 is a nice CV eclipser
about which nothing has yet been published. Another season of data, and
let's us do it. And CD Ind, a local and fairly famous AM Her star. We
want to carry out brief campaigns on many AM Hers to test limits of
synchronization. Most AM Hers are forgotten once they are declared
synchronized, though the data certifying that sometimes only spans a
couple of weeks. With CBA levels of patience, we can apply much more
stringent tests. Who knows, we may find that small amounts of
asynchronism are actually common among these stars!
And finally there's Oph = RX1730-05. Still trying to time that 128 s
That's a pretty wholesale revamping of the CBA sky. Have a great ol'
time observing these stars!
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