From jop at astro.columbia.edu  Fri Dec  5 15:10:24 1997
From: jop at astro.columbia.edu (Joe Patterson)
Date: Fri, 5 Dec 1997 15:10:24 -0500 (EST)
Subject: (cba:news) seasonal trinkets
Message-ID: <199712052010.PAA04050@tristram.phys.columbia.edu>


Dear CBAers,                                          Dec. 5, 1997.

An exciting coupla days.  Cap'n Bob and Dave West sprang into action,
and the data show clearly that TT Ari has switched to a new period,
0.1495+-0.0002 d.  That's Porb+8.7%, whereas the old superhump clocked
in at Porb-3.5%.  Imagine that, it actually switched sides.  Uncharted
waters for TT Ari, and only reported in print for one other star in the
CV zoo.  In our somewhat theory-biased nomenclature, we might say that
it switched from a nodal to an apsidal superhump.

Mighty big amplitude too, 0.18 mag.  Get thee to a telescope.

Jonathan has this week on a 2.4 m telescope.  There's precious little
clear weather, but on his only clear night so far, he found an 80 min
binary period (in LL And, a real bottom-of-the-barrel CV).  The
remarkable thing is its brightness, about 22.5 mag.  I think this may
be the faintest star ever to reveal its binary period from optical
observations carried out on the Earth.  (Please correct me if this is
wrong.)  Not bad for a mere stripling of 24 years.

No change in target priorities.  Get a piece of that fine TT Ari action
while it still lingers in the evening sky.


         joe



From jop at astro.columbia.edu  Sat Dec 13 05:34:38 1997
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sat, 13 Dec 1997 05:34:38 -0500 (EST)
Subject: (cba:news) a new and enticing erupter
Message-ID: <199712131034.FAA10185@tristram.phys.columbia.edu>


Dear CBAers,

Enclosed is the announcement of a probable eruption in a newly discovered
CV which seems likely to be a member of one of our clubs.  Jonathan got
a little photometry last week and found it near 15-16.  Now it's erupted
to 12.9, it appears.  So far the described behavior does not quite fit any
of the suggested classes (WZ Sge/DQ Her), but who knows, the night is
long and full of wonders.  The position is in the announcement below.
Fire at will!

joe

Outburst of RX J0757.0+6306

   H. Itoh (Tokyo, Japan) communicates that the cataclysmic variable
(possible SU UMa-type or DQ Her-type) RX J0757.0+6306 is undergoing an
outburst.  Recent observations:

  YYMMDD(UT)   mag  observer
  971202.672  <137  (T. Watanabe)
  971202.794  <146  (H. Itoh)
  971203.015  <155  (G. Poyner)
  971203.674  <135  (T. Watanabe)
  971204.530  <133  (T. Watanabe)
  971205.667  <142  (T. Watanabe)
  971205.860  <131  (H. Itoh)
  971212.866   129  (H. Itoh)

  The following information is from the vsnet-chat log.

(http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg00662.html)
> Date: Thu, 9 Oct 1997 12:22:48 +0900 (JST)
> From: Taichi Kato <tkato at kusastro.kyoto-u.ac.jp>
> Subject: [vsnet-chat 662] RX J0757.0+6306
> 
>   According to "Astronomical Time Series" (ed Maoz et al. 1997, Kluwer
> Academic Press) p.195, Tovmassian et al. identified the ROSAT source
> RX J0757.0+6306 (=1RXS J075700.5+630602) as a new, ultrashort-period
> cataclysmic variable.  The orbital period is 75+/-1.4 min.  The optical
> spectrum shows strong hydrogen emission lines, resembling that of WZ Sge.
> Tovmassian et al. discussed in this paper the possibility of a DQ Her type.
> This star may be worth monitoring for possible future outbursts.
> 
>   The paper did not mention the accurate coordinates, but watching at
> the ROSAT position (07h 57m 00s.5, +63o 06' 02" 2000.0) might be sufficient.

(http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg00663.html)
> Date: Thu, 9 Oct 97 23:38:25 PDT
> From: Gaghik Tovmassian <gag at bufadora.astrosen.unam.mx>
> Subject: [vsnet-chat 663] RX J0757+6306 (Tovmassian)
> 
> Dear VSNET fans,
> 
> I'm readily support Taichi's call for monitoring 
> RX J0757+6306. Indeed this system has all chances to
> turn into another WZ Sge system or proof to be 
> the shortest period Intermediate Polar.
> Briefly what we know about this system:
> a. It is X-ray source, not much known about spectra or variability in X-rays.
> b. Optical Spectroscopy indicates CV nature with prominent accretion disk 
> 	and hot spot.
> c. Period derived from the S-wave radial velocity variations is
> 	most probably 81 minutes (+/- 5 min are not excluded).
> d. The limitted photometry shows no eclipsing, high amplitude flickering
> 	light curves. On 4 ocassions out of 5, significant signal was recorded
> 	at frequency corresponding to 8.5 min  oscillations.
> e. No outburst history is available at the moment.
> 
> The POSS measurments of coordinates and magnitude are as follows:
> RA 07h57m01.3s  DEC +63d06m01s   2000.0   16.06 (red)
> 
> The identification chart is posted to VSNET separately.
> The system was reported by Tovmassian et al. in  Proceedings of 
> Symp. dedicated to 25th aniversary of Wise observatory
> "Astronomical Time Series" (ed Maoz et al. 1997, Kluwer Academic 
> Press) p.195
> and 13th NorthAmerican Workshop on Cataclysmic Variables,
> in press.
> 
> Regards, Gaghik Tovmassian
>  OAN, IAUNAM, Mexico

(http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-chat/msg00664.html)
> Date: Fri, 10 Oct 1997 16:25:06 +0900 (JST)
> From: Taichi Kato <tkato at kusastro.kyoto-u.ac.jp>
> Subject: [vsnet-chat 664] RX J0757+6306 chart
> 
> Dear Colleagues,
> 
>     I have put the finding chart of RX J0757+6306 kindly provided by
> Dr. Tovmassian on the VSNET WWW/ftp.  The JPEG file is at the URL:
> 
> ftp://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/CVs/RXJ0757/rxj0757p63_fchart.jpg
> 
>     Please monitor this object, and report your (either positive or negative)
> observations to vsnet-obs.
> 
> Best regards,
> Taichi Kato

   Confirmation is most urgently requested; follow-up high-speed photometry
is also urgently requested.

Regards,
Taichi Kato


From jop at astro.columbia.edu  Wed Dec 17 09:12:48 1997
From: jop at astro.columbia.edu (Joe Patterson)
Date: Wed, 17 Dec 1997 09:12:48 -0500 (EST)
Subject: (cba:news) timing conventions; let a hundred times bloom
Message-ID: <199712171412.JAA20607@tristram.phys.columbia.edu>


Hi CBAers,                                            Dec. 17, 1997.

Comments re Paul's comments re heliocentric correction.

Some time ago we decided that the "standard" for reporting times is JD
rather than HJD.  This was mainly because, in theory, every step of
data massage introduces some possibility of error, and I would like all
the errors to occur on *my* desk, not someone else's -- because then
there is some chance of catching them!  On the other hand, we use
different software, and some programs automatically slap the
heliocentric correction on the times.  That's fine as long as I know
it.  It's important to label the time JD or HJD or UT, but I can easily
cope with any of these.  But do it the same way every time.  I'm not
asking that anyone change, because I think I've learned everybody's
system!

It's also helpful to label the UT date of the observation, because that
lets me check the JD's accuracy.  There have been a few errors of +-1
in JD, but I've been able to spot them with the calendar date supplied
(and occasionally also from outlier points when tracking these periodic
processes in CVs).

"Var-Comp" is another source of possible confusion.  That's the
convention, but it has the feature that larger numbers mean fainter.
Still I strongly prefer that because it is such a long-established
convention.

Nice contributions from the Pacific Rim on TT Ari (Gordon G, Paul W,
and Seiichiro K the Balcony Man)!


              joe



From jop at astro.columbia.edu  Mon Dec 22 16:48:02 1997
From: jop at astro.columbia.edu (Joe Patterson)
Date: Mon, 22 Dec 1997 16:48:02 -0500 (EST)
Subject: (cba:news) The 1997 Haul...
Message-ID: <199712222148.QAA02551@tristram.phys.columbia.edu>


Dear CBAers,                                            Dec. 22, 1997

What a great year it's been!

It's hard to even count all the nice things that came our way this
year.  We found two really bright, powerful superhumpers in TT Ari and
V592 Cas.  I believe that our study of these stars will provide the
world's basic information on the long-term evolution of apsidal
superhumps.  And they are bright enough for the humblest of our
telescopes, the 8-inchers with crummy skies.

Three unexpected, essentially new dwarf novae popped up in the spring
and received intense coverage: V844 Her, VW CrB, and USNO pile-o-
digits.  We found accurate periods for each, and they were all short:
79, 80, and 81 minutes.

We found another dwarf nova with an ultra-short recurrence period: V803
Cen, outbursting every 22 hours.  Poster star for global photometry!

We found the orbital period of AM CVn, at 1028.7 seconds.  Searched for
intensively since the early 1960s, and now found.

We amassed a huge study of EG Cancri, king of the echo outbursts.

We greatly extended our study of the SW Sex stars, which seem so
remarkably enamored of negative superhumps.

And much else besides.  On the empire side of the ledger, we enrolled
new observing stations in New Zealand, Russia, and South Africa.  The
New Zealand connection has been superb, with three productive observers
(Stan Walker, Paul Warhurst, and Marc Bos).  CBA-Illinois, under
Jerry Gunn, also came on board and is proving to be a strong node in
our network.

And Jonathan has got a good web site up and running.  (You make him
happy when you visit it.)

So there's all that to be thankful for.  I think it was a year of good
health for CBAers too, though my morning mail has less information
about that than about the latest celestial wiggles.

And what for the new year?

The strategy on V592 Cas and TT Ari is similar.  For both stars, we
have obtained intervals of ~15 d of *dense* coverage, which permits
sensitive searches for periodic signals.  And the results are fairly
simple: very stable apsidal superhumps at 0.1223 and 0.1492 d
respectively (with a few harmonics as usual).  That project is done.
The second project is to study slow period changes by tracking the
signals as late as possible in the observing season (Jan 20 maybe?),
then resuming as early as possible next year.  In effect, that means
the stars remain ideal targets for the smallest and most northerly
telescopes.  But the bigger telescopes and those below +40 degrees
should probably sign off.

     The observing season has also ended for V503 Cyg, FO Aqr, and
PX And.  I still hope for late-season timings of AO Psc, though.

     A really good star for coverage now is "Tau 2" (the name in
Downes-Webbink-Shara, where there's a chart).  It has V~15.5 and is
accessible to everyone at J2000 4h 00m 37.3s, +6d 22m 46s (2 arcmin SW
from a bright star).  Still unstudied, but a promising applicant for
one of our clubs (SW Sex or DQ Her).  If you can use the bright star as
a comparison without saturation, do so; otherwise trust your judgment
and tell me which comparison you used.

     Another good one is "Tau 1" = V1062 Tau.  Candidate periods at 10
and 1 hr.  This one's a little harder at 16.  Chart in the original
Downes-Shara.

     CN Ori is also good any time (quiescent or erupting), and RZ LMi
is good if in eruption (which it does quite a lot).

     For the Australites, AH Men = Men 1 and RR Pic are the targets of
choice these days.  Bright and southerly and humpy.

     Finally here are a couple of truly weird ones, emission-line stars
that live in small gamma-ray (100 MeV) error boxes.  We dunno what they
are, but two types of measurement would be nice: BVRI magnitudes (for
those with filters) and nightly delta-mags with respect to a fixed
comparison star.  A time series might be good too, who knows?  Here are
their J2000 positions:  22h 26m 38.7s, +61d 13m 32s; and 06h 35m 18.3s,
+05d 33m 06s.  Each has V near 12.2 (I think).  The second one has a
13th mag star, a promising comparison, about 30" N of it.  But the
first is on the edge of a dark cloud, and you're on your own!  Happy
hunting, lemme know what you find!

     Now I get to go off for my own winter holiday.  And I have a new
modem now, so please write!


                             joe



From jop at astro.columbia.edu  Mon Dec 29 10:17:55 1997
From: jop at astro.columbia.edu (Joe Patterson)
Date: Mon, 29 Dec 1997 10:17:55 -0500 (EST)
Subject: (cba:news) ty erupts at last
Message-ID: <199712291517.KAA14297@tristram.phys.columbia.edu>


Dear CBAers,                                           Dec. 29, 1997.

Finally our buddy TY Psc has jumped into superoutburst, and Jonathan
found the expected superhumps blazing away at 0.25 mag amplitude last
night.  At V=12.2, the star is a very peachy target for small-scopers.
And should remain so until the Moon interferes in about 10 days.  The
exact 2000 coords are 1h 25m 39.35s +32d 23m 10s.  We're using a
V=13.25 mag comp star located 0.27 arcmin W and 2.85 arcmin S from
the variable.  You'll like this one, the light curve is a beauty!

The reason I'm so eager for TY Psc is that it's basically the last of
the bright northern SU UMa stars without a known precise superhump
period.  Not counting the very rare erupters, which can be wished for
but not really planned for, and a few miscellaneous stars which are not
known to possess, but might turn out to possess, the standard SU UMa
credentials.

So that's a great evening target for most stations.  TT Ari and V592
Cas also continue to hump away, and scattered hump timings through the
rest of the observing season are needed (say a 3 hr observation once a
week).

The only other development is that I'd like to take Tau 2 off the menu.
Cap'n Bob got three straight nights on it, and it was disappointing.
Tau 1 = V1062 Tau, on the other hand, looks to be very interesting.
Warren Offutt's data showed the 59 min signal very plainly, so let's
fire away on this star.  Nicely placed in eastern Taurus.  There's also
an alleged 10 hr signal, so very long runs would be nice.  The other
all-night object is CN Ori at quiescence; about 15.7 but with a
very large hump.

Then there's RZ LMi and DI UMa whenever they erupt, which is very
often.  Up in the 14s and quite feasible for borealites.  Australites
keep the faith on AH Men, RR Pic, and CN Ori.

Warren and Stan Walker report good results with Rudolf Novak's MuniDos
reduction program for time-series photometry in a DOS-friendly setting.
That might be of much interest out there, since I know many of you are
still looking for a good data reduction pipeline.


        joe