From jop at astro.columbia.edu  Thu Jun  7 15:19:20 2001
From: jop at astro.columbia.edu (Joe Patterson)
Date: Thu, 7 Jun 2001 15:19:20 -0400 (EDT)
Subject: (cba:news) stars for june
Message-ID: <Pine.SOL.4.05.10106071436330.8709-100000@tristram.phys.columbia.edu>


Dear CBAers,                                             June 7, 2001.

Time for a report on those helium stars!

We've ended the V803 Cen campaign, as most of you know.  It was entirely
successful, yielding a definite orbital period and thus a precise value
for the fractional superhump period excess (0.0040, implying a
secondary-star mass of 0.013 Mo).  This was suggested by the 1999
campaign, and proved by this year's.

The HP Lib campaign has only been going 24 days, yet it too should be
declared about over.  I've been trying to measure HP Lib's Porb for years,
but always failing - the strong superhump really veils the weaker orbital
signal.  But this year the New Zealanders went hard after it (especially
Bob Rea, but also Fred Velthius, Jennie McCormick, Bill Allen), and the
regularity of the coverage brought out that little orbital signal at
1103.3 sec (compared with the superhump at 1119.2 s).  It's very small,
just 0.002 mag in amplitude, but quite established nevertheless.  I'm
really thrilled about that - the amateurs did what we couldn't do with
40-inch and 52-inch telescopes 2 years earlier!

We need to keep going on CR Boo.  We're getting some coverage from many
people, though no one has managed to string together a long series of long
nights.  There appear to be three characteristic periods in the star, at
~1491 s, 1487.3 s, and 1471.0 s.  This makes for quite complicated power
spectra, and because our sampling is complex too (many short observations
from different longitudes), it's quite hard to disentangle.  Let's try for
2 more weeks on CR Boo!
____________________________________

    That's the helium stars.  Now for other stuff.

    The best southern target right now is V551 Sgr, if indeed it is
staging a superoutburst - is it? look for the telltale superhumps!
2000 coords 18 00 56.2  -34 35 42  Obvious for NZ/AU.  But it would be
nice if others would try it, as that would break aliases and permit easy
period-finding.  Even if it doesn't immediately show superhumps, it still
probably will within a few days, assuming it stays bright.  Helluva field,
as usual in that unhappy constellation.

    The other southern is V2400 Oph = J1712-2414, which at 14.4 is a
bright and interesting - and little-studied DQ Her star.  Complex period
structure, which we want to master.

    And for the north, it's CR Boo and V795 Her.  Finally, it's time for a
long campaign on this bright northern CV - V795 Her - which we have not
managed to effectively study since we spread out in longitude.
17 12 56.09  +33 31 21.4

Plus some help for the wintry south on V2400 Oph.


            joe



From jop at astro.columbia.edu  Fri Jun  8 09:00:16 2001
From: jop at astro.columbia.edu (Joe Patterson)
Date: Fri, 8 Jun 2001 09:00:16 -0400 (EDT)
Subject: (cba:news) V551 Field (fwd)
Message-ID: <Pine.SOL.4.05.10106080857540.29193-100000@tristram.phys.columbia.edu>


Oops, Bill Allen notes that finding this little fella may not be so easy.
Can anyone get a secure ID and precise position?

joe

---------- Forwarded message ----------
Date: Fri, 8 Jun 2001 11:54:15 +1200
From: Bill Allen <wallen at voyager.co.nz>
Reply-To: Bill Allen <bill.allen at voyager.co.nz>
To: Joe Patterson <jop at astro.columbia.edu>
Subject: (cba:news) V551 Field

Joe,

Do you have a chart of this one ? I can not find a chart on your website.

I have used Guide 7 to get a chart of V551 and have found the area all right.
 However I can not be sure that I have found V551.    Is V551 in a nebulous 
region as a hazy patch appears in the centre of the CCD frame when centred 
on V551. The hazy patch disappears when centred on a star a couple CCD 
frames away. Perhaps its the moon as its not far from V551.

Regards,

Bill Allen.




From jop at astro.columbia.edu  Sun Jun 10 07:17:56 2001
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sun, 10 Jun 2001 07:17:56 -0400 (EDT)
Subject: (cba:news) Hercules reappears in strength
Message-ID: <Pine.SOL.4.05.10106100650570.20415-100000@tristram.phys.columbia.edu>


Dear CBAers,

Two new targets in Hercules have popped up.

Tonny's announcement of superhumps in V478 Her is enormously important, as
the apparent long period (3.1 hrs) puts the star at the very end of the
Porb distribution for dwarf novae.  It's very well placed for northern
observers, and at +23 deg I can have some hope (can't I?) that some of the
more northerly AU-NZ folks can study it.  (Neil?  Gordon?  Stan?)  The
2000 position is 17 21 05.60  +23 39 36.9; chart in Downes-Webbink-Shara
(PASP 4/97 catalogue as well as the current on-line version).

Definitely a cutie.  Watch out for scattered light from that nearby bright
star.  The variable is probably ~15.8-16.0 and fading, so demands pretty
good conditions.  Send data to Tonny too, by the way.

I also today received from Dave East the first observation of the season
for V795 Her.  This star - usually called a "novalike variable" -
showed a bodacious 2.8 hour superhump in the 1970s-80s, which
promptly disappeared for many years.  (We looked, too.) Every so often we
look in to see if the humps will come back - in which case we can study
them.  Since the star has V~12.5 practically all the time, it would be a
really nifty target.

Well it appears to be back.  Can't tell for sure yet from one night, but
we should take a few more nights and then, if the hump's indeed there,
launch a full campaign.  2000 coords 17 12 56.09  +33 31 21.4, chart in
Downes-Shara as well as online version.

V478 Her is definitely of higher priority right now, since it is eruptive
and has a candidate period of high intrinsic interest.  Go for it!


            joe



From jop at astro.columbia.edu  Mon Jun 11 09:49:24 2001
From: jop at astro.columbia.edu (Joe Patterson)
Date: Mon, 11 Jun 2001 09:49:24 -0400 (EDT)
Subject: (cba:news) V478 Her dives outa sight
Message-ID: <Pine.SOL.4.05.10106110946350.258-100000@tristram.phys.columbia.edu>


Sorry folks, V478 Her went pretty faint over the last 2 days, probably
around 17 or fainter.  That means it's out of our universe.  Tonny may
have caught it late in the outburst, or... well, anyway, this elevates
V795 Her in priority for northern folk.  And the watch continues for CR
Boo.

      joe



From jop at astro.columbia.edu  Wed Jun 27 17:38:24 2001
From: jop at astro.columbia.edu (Joe Patterson)
Date: Wed, 27 Jun 2001 17:38:24 -0400 (EDT)
Subject: (cba:news) new stars and campaigns
Message-ID: <Pine.GSO.4.33.0106271723530.17574-100000@fidelio.phys.columbia.edu>


Dear CBAers,

Sorry I've been so silent.  Been off on a short vacation, and a long
episode of very crippled access to email.  A victim of the ol' upgrade
syndrome.  Perhaps everything is OK now.

Here's a quick summary...

Best northern target is still V795 Her, gloriously superhumping again
after a 12-year hiatus and definitely worth a few more weeks of coverage.

Best southern target is still V2400 Oph.

But the other good target, suitable for both hemispheres, is V1494 Aql...
the bright nova of fall 1999, now flashing at us such an odd set of
periodic signals.  (Though we haven't actually peered in since last fall.)
2000 coords 19 23 05.38 +04 57 20.1.  This will be our primary target in a
few weeks, and I hope some of you will start observing it intensively
right now!

Then there are the summer/winter DQ Her stars... we like to monitor these
for the ever-changing pulse periods.  The biggies this time of year are
V1223 Sgr, AO Psc, and FO Aqr.  Good for even fairly short observations.

Oh, and the CR Boo campaign is DEFINITELY OVER.  Just a little too late in
the observing season for really good data.


                 Joe


From jop at astro.columbia.edu  Thu Jun 28 20:12:38 2001
From: jop at astro.columbia.edu (Joe Patterson)
Date: Thu, 28 Jun 2001 20:12:38 -0400 (EDT)
Subject: (cba:news) ES Dra
Message-ID: <Pine.GSO.4.33.0106282010310.18747-100000@fidelio.phys.columbia.edu>


Dear CBAers,

Tonny's report on ES Dra sounds pretty interesting - and the star is
decently placed.  Let's take advantage of the outburst and send some
spanking new data his way!

     joe