From jop at astro.columbia.edu  Thu Jan 15 21:50:08 2009
From: jop at astro.columbia.edu (Joe Patterson)
Date: Thu, 15 Jan 2009 21:50:08 -0500
Subject: (cba:news) january targets
Message-ID: <496FF5E0.4090007@astro.columbia.edu>

Dear CBAers,

Sorry for letting the current targets get a little brown around the 
edges!  I've been taking advantage of the Xmas break to write up papers, 
and have been keeping up with the data you've sent.  But the eruptions 
have faded, the year has turned, and... time for a new menu.

    Dwarf nova eruptions are by their nature unpredictable, and the most 
interesting ones are faint and mighty rare.  So these are, at least for 
now, in abeyance.  Every January, though, a host of DQ Her stars rolls 
around in a good sky position.  We haven't seen any of 'em in 8 or more 
months, so they're all ripe for sharpening the period measurement 
(through lengthening the baseline).  *Both* periods - rotational and 
orbital... with an outside chance of another one (superhump or some such 
thing) jumping up and saying hello.

    The fairly easy stars to do (no great challenges in terms of 
brightness) are:
IGR0023+61 = RX0022+61
V405 Aur (0558+53)
RX0625+73 = MU Cam
RX0636+35 = "Aur"
BG CMi (0729+103)

The slightly harder stars to do are:
RX0704+26 = Gem
Swift0732-13
DW Cnc (0758+16)

Now our usual strategy for practically all stars is to stay on one 
target all night long (or substantially all night).  That always gives 
the best chance of finding something altogether new.  And in this case 
that might be true too - adopt a star and stay on it for two weeks!  But 
strictly for the purpose of accumulating pulse timings - and thereby 
tracing out the long-term period change, it's better to knock these 
stars off in little 3-hour segments, jumping around the sky from star to 
star.  Then it might be feasible to track most or all of the targets.
Take yer pick!

There are a few exceptions to this call for a long assault on the DQ Hers.

1. T Pyx. I'm just finishing a paper on the 1998-2008 timings.  It would 
be nice, and easy, to fold in the 2009 timings.  About 2 weeks of solid 
observation will no the trick.

2. V436 Car. This continues to haunt me.  We've had one decent campaign, 
but never a really good one.  The star has a very, very high proper 
motion , suggesting it's very nearby.  But we still just haven't figured 
out the periods.  Perfectly timed!

3. AM CVn.  Same comment as T Pyx.  But unlike T Pyx, it's still just a 
touch early in the observing season.

And lots of CBA correspondence to catch up on. That's what tomorrow is for!

joe


From jop at astro.columbia.edu  Wed Jan 21 21:28:17 2009
From: jop at astro.columbia.edu (Joe Patterson)
Date: Wed, 21 Jan 2009 21:28:17 -0500
Subject: (cba:news) T Leo (QZ Vir) and 0329+12
Message-ID: <4977D9C1.2050005@astro.columbia.edu>

Dear CBAers,

Patrick Schmeer found T Leo (QZ Vir) at 11th magnitude yesterday, in a 
possible extraterrestrial display of Obamamania.  Is it a superoutburst? 
  Someone probably knows already, but has not yet reported.  But the 
chances are quite good.  It's a very good season for Leo, and the 
equatorial location is good for all.  A good chance to get very 
extensive coverage of this quite nearby star - let's make it a major 
target!  Assuming it's a super - the humps are the dead giveaway.

Taichi Kato's post below makes 0329+12 a very tempting target too.  Very 
little known about this star.  Personally I'm a little skeptical of this 
one... but it's really important if it's true!

My observing class starts tomorrow, and I return to regular nightly 
observing for the first time in about 15 years.  Wow!  Not many CVs on 
the agenda in our milky New York skies... but it should be lots of fun.

Fire away, and let us know what you find on these interesting stars!

joe

-------- Original Message --------
Subject: [vsnet-outburst 9927]  OT J032912.3+125018 possible outburst
Date: Thu, 22 Jan 2009 10:25:13 +0900
From: Taichi Kato <tkato at kusastro.kyoto-u.ac.jp>
To: suuma at yahoogroups.com, variable_star_forum at yahoogroups.com, 
vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp, 
vsnet-alert at yahoogroups.com, 
vsnet-campaign-dn at ooruri.kusastro.kyoto-u.ac.jp, 
vsnet-outburst at ooruri.kusastro.kyoto-u.ac.jp,	vsnet-outburst at yahoogroups.com

OT J032912.3+125018 possible outburst

   ASAS-3 possibly recorded an outburst of this object (=VS 0329+1250),
an SU UMa-type dwarf nova with a very short superhump period.
Confirmatory observations are encouraged.  If confirmed, time-resolved
photometry is strongly encouraged!

   YYYYMMDD(UT)   mag  observer
   20090112.0609 <14.50V  (ASAS (Pojmanski, G. 2002, Acta Astron. 52,397))
   20090115.0560 <14.50V  (ASAS (Pojmanski, G. 2002, Acta Astron. 52,397))
   20090118.0571 <14.50V  (ASAS (Pojmanski, G. 2002, Acta Astron. 52,397))
   20090121.0559 13.878V  (ASAS (Pojmanski, G. 2002, Acta Astron. 52,397))



From jop at astro.columbia.edu  Sun Jan 25 09:30:56 2009
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sun, 25 Jan 2009 09:30:56 -0500
Subject: (cba:news) T Leo = QZ Vir is a super
Message-ID: <497C77A0.9090305@astro.columbia.edu>

Dear CBAers,

Four days ago, a run by the Razorback gang (Campbell-Roberts-Robertson) 
showed T Leo bright and with strong periodic waves - but rapidly 
declining.  This was confusing.  But these reports by Stubbings and Kato 
make it seem very likely that it was simply the trigger to a supermax. 
So T Leo is very likely at the beginning of a well-placed supermax. 
Fire away with all available weapons!  It's a great opportunity for very 
close study of bright superhumps over the full duration of outburst.

I think the original brightening occurred just as Obama was taking the 
oath - proof that the original oath-taking was probably considered valid 
by Galaxy-wide standards.  Just to placate the purists.

joe

-------- Original Message ------

QZ Vir has rebrightened to a superoutburst.

VIRQZ          090125.532   100

Regards,
Rod Stubbings





> QZ Vir rebrightened to a superoutburst?
>
>  YYYYMMDD(UT)   mag  observer
>  20090117.3750 <14.50V  (ASAS (Pojmanski, G. 2002, Acta Astron. 52,397))
>  20090120.3330 <14.50V  (ASAS (Pojmanski, G. 2002, Acta Astron. 52,397))
>  20090121.087   110  (Patrick Schmeer)
>  20090124.3213 13.317V  (ASAS (Pojmanski, G. 2002, Acta Astron. 52,397))
>  20090124.549   116  (Rod Stubbings)
> 



From jop at astro.columbia.edu  Thu Jan 29 15:48:17 2009
From: jop at astro.columbia.edu (Joe Patterson)
Date: Thu, 29 Jan 2009 15:48:17 -0500
Subject: (cba:news) [Fwd: Request for Observing BG Gem.]
Message-ID: <49821611.6000900@astro.columbia.edu>


HI CBAers,

This looks like a good CBA project.  Mark wants coverage of BG Gem over 
a 90 day period.  It's bright enough for us, and he merely needs (I 
think) differential photometry with respect to that marked comparison 
star.  Of course, he doesn't need a full time series, since it's a 90 
day period... but get enough points that he can assess the random error 
of the observation.  BTW it seems to be a filters-only project.

Among the CVs, keep firing away at T Leo = QZ Vir!

joe




Dear Fellow MDM Observer

I have been granted time for a program of photometric observations of the
black hole candidate BG Geminorum at the MDM 1.3m. The aim of these
observations is to significantly improve the poorly constrained
ephemeris. The orbital period of this binary system is approximately 90
days, as such observations will be required over a number of months.

As BG Gem is bright at optical wavelengths (V  13), these observations
will be short (30s x 4 in each lter). We do not require standard star
observations as we have previous observations during which this eld was
calibrated. In total, the estimated time per night (acquisation +
exposure) should be no more than 10  15 mins.

We request imaging in the V, R & I-band lters every night, or as close to
this as possible (Feb 1st  May 1st ). In the event that observations are
possible with only a single filter, we prioritise observations in the
R-band.

See my BG Gem webpage

http://www.astro.lsa.umich.edu/~markrey/bg_gem/bg_gem.html

for background information, nightly observing window, charts and the quasi
real time lightcurve.


BG Gem, V mag :  13
= 06 03 30.81,  = +27 41 50.7

Filter                                 Integration Time     # Exposures
========================================================================
V                                      30                       4
R  --  highest priority                30                       4
I                                      30                       4

I'll be observing at the MDM myself on a number of occasions over the
coming semesters and will be more than happy to return the favour at some
stage in the future.

regards,

Mark Reynolds

markrey at umich.edu
+734 764 4160


**************************************************************
**************************************************************
BACKGROUND INFORMATION (this info will also be on the website)

Title : Updating the Ephemeris of BG Geminorum

BG Geminorum is a long period eclipsing binary system (Porb  90 days);
currently the nature of the primary is uncertain. Recent observational
evidence indicate that the primary star is a black hole. If so, BG
Geminorum would be the black hole binary system with the largest orbital
period, by a factor of 3, as well as being the only known eclipsing black
hole binary system in the Galaxy.  Here, we propose optical monitoring
observations with the MDM 1.3m, which will contrain the orbital ephemeris.

Based on the mass function, mass ratio (q  M2 /M1 ) and the inclination
angle, in combination with the observed maximum emission line velocities
in the UV & optical spectra, the primary star in BG Gem is either (i)
B-type star (ii) a stellar mass back hole.

The ephemeris for BG Gem is currently poorly contrained. The current error
on the time of eclipse large, e.g. our NOT spectra do not display high
velocity emission lines; however, due to the large uncertainties in the
time of eclipse, it is possible that the black hole in eclipse during
these observations. Clearly, this is an unsatisfactory situation.

Here, we propose to obtain optical monitoring observations of BG Gem
throughout its entire 90 day to accurately constrain the binary orbit.
Plus...... other relevant science case info and images, i.e. previous
spectra are available at the web site.



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