(cba:news) january stars

Joe Patterson jop at astro.columbia.edu
Mon Jan 13 10:06:07 EST 1997

Dear CBAers,                                              1/13/97

Well, howdja like that.

No sooner do I warble the praises of BZ UMa than it disappears.  Bah.
Those damn short outbursts.  Then I chide EG Cnc as a non-performer,
and Bob Fried sends me three long nights with great-looking superhumps.
So much for "the experts".  Take this message as replacing the one of
three days ago, which turned out to be not too smart.

EG Cnc is still a good target, especially if you have already built up
an investment.  Just how good it is depends on its eruptive history in
the near future, which of course nobody knows.  It is however
superhumping continuously, and I think has been since December 5.  In
addition to the time series, multicolor photometry or spectrophotometry
would be of high interest, as the star has been changing its spectral
slope a lot in these "echo" outbursts that it is now flashing to the
wonderment of all.

Our main star this month is nevertheless BH Lyn.  Alon Retter has the
Wise Observatory 1-m scheduled for this star during Jan. 19-26.  The
Israeli weather isn't very good in January, and there's a bright moon;
but with the northerly dec and the long winter nights, it's still a
fine occasion to try for real round-the-world coverage.  Dave Skillman
and Lasse Jensen have made friends with the star already, and verified
that it's waving and eclipsing and doing those fine things that we
like.  Go Japan and Hawaii, we're hoping!

The other two SW Sexers burrowing their way into the night sky are DW
UMa and SW Sex.  We'll do intensive campaigns in Feb-Mar-Apr, but some
morning visits now would be nice.

Lasse got a long run last night on RZ LMi which showed fine superhumps.
So let's have a word about this star.  We got some fine data two years
ago, which suggested (but did not prove) that the superhumps actually
maintain phase from one superoutburst to the next.  At least they did
for five in a row.  That would be remarkable and I wanted to study it
some more.  But things came up, and the project got shoved aside.  Now
I'm thinking about it again.  The star has supermaxima just 19 days
apart, so with foresight we could basically sample the superhumps of
about the next six supermaxima, with no huge effort involved.  Six more
would make a believer out of me.  If some of the bigger telescopes in
our network (Wise, Ouda, CBA-East) could add in a few time series at
quiescence, we could find out if the means for such good phase memory
is basically superhump continuation at quiescence (which I conjecture
is also true).  So this is in my opinion an excellent season-long
project to plug away on.

Now about snapshots.  Not of course a specialty of ours, but in
the case of CR Boo we learned a great deal from them.  There are
definitely a few stars in our program which have sufficiently little
known about their pattern of variability that snapshot coverage is of
high value.  These are: V803 Cen (dum-da-dum-dum, big target this
year on all time scales!), CR Boo, HS Vir, Ser 1=PG1510+234, CP Eri,
and Hya 1=PG0911-066.  The three helium stars in the list aren't in
Downes & Shara, who didn't like helium; so we'll get the charts
prepared and posted (I think CR Boo and V803 Cen are already posted).
The last three stars are usually a bit faint, so you'll need longish

I realize that some CBAers are not so well set up for time series, but
could contribute greatly with snapshots.  Please let me know who you


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