stars of the new year

From: Joe Patterson <*jop_at_astro.columbia.edu*> Date: Sat, 28 Dec 1996 16:40:45 -0500 · jop_at_astro.columbia.edu

Dear CBAers,                                             12/28/96

     Another report of progress and plans.

     Bad weather and vacations and bright moon have afflicted us over
the past 10 days.  Our coverage seems to have slipped although I can't
be sure since some of you are in the habit of surprising me with a
couple weeks data sent at a time.  I watch my box carefully for such
tidings of comfort and joy.

     Most of you know that EG Cnc surged a few times after the main
outburst, and indeed it may not be over.  Humps remain in the light
curve (they might have disappeared for a day or so, but they're
generally still there at low amplitude), though we have not lately
got the extensive multi-longitude coverage that makes period-finding
easy.  Let's keep the faith for at least another week.  (But probably
not for ye of little aperture; the star was 16th mag tonight, and may
have disappeared from your menu of feasible targets).

     There's at least three more weeks of life left in the PX And
campaign.  Feed me, feed me.

     It's time to quit on RW Tri.  This has been a backup target,
mainly for the Europeans.  I wanted to do some stars "expected not to
show superhumps", because it's always dangerous to tailor your
observing program strictly for the most promising stars.  I certainly
don't think that bias is absent from our work, but I would like to
lessen it.  RW Tri followed conventional wisdom in failing to superhump
even with a sensitive detection limit of ~0.04 mag.  A good result, and
a damn handsome light curve too.

     The other backup target we're doing is FY Per.  Nice bright star,
suitable for bright moon, small telescopes, poor conditions.  We should
keep going on it through March 1.

     Now for the main course.  The excellent luck we've had with DW UMa
(last year) and PX And leads me to place a heavy emphasis on covering
all the SW Sex stars.  In particular, three of these stars are now
swinging into good observing position for northerners: BH Lyn
(0822+51), DW UMa (1030+59), and SW Sex (1012-03).  It's now time to
begin campaigns on each of these stars.  I propose that we do an
intensive campaign from now through January 16 on BH Lyn.  If it
superhumps, we'll be wanting to cover it for two more months -- but we
want one episode of intense coverage to reach sensitive limits and to
unravel the (often) fine details of period structure.  A good-looking
comp star (V=14.47, B-V=0.76) lurks 1.3 arcmin NW from the variable,
and another possible one is 2 arcmin S from the variable.  Either is
OK, with the former preferred.  The variable is in Downes & Shara, with
2000 coords 8 22 36.1  +51 05 24.

The time is ripe for starting on DW UMa and SW Sex too.  DW is in a
very blank field; I recommend a comp star 5 arcmin W and 3 arcmin S
from the variable (off the Downes & Shara chart).  SW Sex has a really
good comp (V=13.19, B-V=0.64) 2.1 arcmin E and 1.2 arcmin N from the
variable.

I hope that the dwarf novae will let us do these programs!  The only
dwarf nova I would assign comparable importance to is DI UMa, but that
one is probably too faint for the smaller scopes.

More on dwarf novae later... but let's get going on the SW Sexers and
especially BH Lyn.

Oh, such a NORTHERN bias!  Well, I'll write again re the southern
stars, but the one word summary is: Tafelberg (alias Men 1, alias H
0551-819)  We'll do intensive observations of it from Chile during
January 2-19, and would dearly love help from other longitudes.  Go
ahead and include its companion star in the aperture, we'll figure out
how to deconvolve it later.

     joe