(cba:news) stars of march

Joe Patterson jop at astro.columbia.edu
Sat Mar 1 01:49:54 EST 1997

Dear CBAers,                                         March 1, 1997.

OK, I have the S. African mail link set up now.  You can reach me at
jop at astro.columbia.edu.  That's the preferred address for letters, whereas
Columbia is still preferred for data.  But either is fine.

We've just finished a mini-campaign on BH Lyn and DW UMa.  One of those
full-moon specials, sorry about that.  Weather at all stations ranged
from average to very poor, so our haul was pretty thin.  But we got
enough to close the books happily on BH Lyn for the observing season.

DW UMa continues to be of extraordinary interest, and I certainly hope
you make friends with this excellent star.  We will be working
on it as the prime target for many (most) of us for the next six weeks.

Now there's still EG Cancri.  Still superhumping a couple of weeks ago
at magnitude 17.4.  Now probably a little fainter; the Ouda photometry
placed it at 17.85.  Keep close watch for further echoes.  I think the
"star of the week" folks have turned away from it, and the likelihood
that humans will see another echo is not great (the echo only lasts ~1
day).  So let's us do our part.  Even if you can't get time series,
snapshot photometry would be very useful (including upper limits).
(Warren, this is a good target for your occasional potshots.)

Which brings us to... er, the star of the week.  Namely, T Leo, back in
superoutburst after about 4 years.  Until this Xmas, I would've said it
was "just another SU UMa star", with Porb and Psh known, so why bother?
The reason is: ECHO OUTBURSTS.  EG Cnc may be the king of echo
outbursts, but T Leo has flung a few at us in the past, and because it
is the brightest of the known echoers, it could provide crucial
information on just what are these strange surges in light.  In
addition, T Leo is very bright and equatorial -- so all of us can do
it, and it's great for the small-scopers who have trouble with the
fainter stars.  Could you let me (and everyone; send to cba-news) know
if you have gotten or expect to get time series on this star?  I'm
somewhat reluctant to declare a campaign now for fear that our coverage
will be too sparse -- but if at least three of us are planning to do
it, then I think we should all pitch in.

As some of you know, the April PASP will be a special issue on CVs,
including an updated Downes-Shara catalog.  We'll send it out to all
nonprofessional CBAers.

So the star I am really plugging for all northerners is DW UMa.  But
I'm also hoping to get a campaign going on SW Sex (1012-03), which is
now in good position for obervers everywhere.  If nobody salutes I'll
abandon this star, since our investment so far is very small; but I
thought I would keep trying.

Finally there is V803 Cen.  From March 25 through April 19 we have
telescopes in South Africa and Chile scheduled for intensive
observation of this guy.  Snapshot observations before and after this,
and in a perfect world *time-series* photometry, would be of great

Even more finally, there is AH Eri.  We've been waiting all season for
an eruption, and it finally happened.  It's late enough that each
observer can get only brief runs, but by using several longitudes we
can probably solve the period-finding problems.  The star is of great
interest because it may contain a magnetic white dwarf in a dwarf nova
binary, an awfully rare beast.  There has never been any time-series
photometry in outburst.  See what you can get, this could be
sensational (to those of us who care).  It was 12.1 yesterday, I
haven't the foggiest idea how long the eruption will last.


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