From jop at astro.columbia.edu  Sun Jun  1 18:13:16 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sun, 01 Jun 2008 18:13:16 -0400
Subject: (cba:news) SDSS 1627+12... and GW Lib
Message-ID: <48431EFC.1090607@astro.columbia.edu>


Dear CBAers,

Well, Tom found superhumps in this interesting star last night.  The 
period is long enough to merit special attention, and placement in the 
sky could hardly be better.  Great target for borealites.

As for australites, oh, it's GW Lib!  The star is back flashing its 2.1 
hr waves in the light curve, it's a great target for those southern May 
nights, and we'd like to track that wave throughout the observing season.

Later on today, I'll send info on MV Lyr.  Jerry Foote and Bob Koff have 
obtained some very nice data, and I'll test for the orbital signal which 
would be the signature of reprocessing.  My quick study of the first two 
nights suggested no (which is interesting too, because it sets a limit). 
  But I'll study further...

joe

-------- Original Message --------
Subject: 	[cvnet-outburst] SDSS J162718.39+120435.0 superhumps detected!
Date: 	Sun, 01 Jun 2008 07:18:12 -0600
From: 	Tom Krajci <tom_krajci at tularosa.net>
Reply-To: 	cvnet-outburst at yahoogroups.com
To: 	cvnet-outburst at yahoogroups.com, chat CBA <cba-chat at cbastro.org>,
baavss at yahoogroups.com
References: 	<g1q7as+96pi at eGroups.com>



Time-series photometry last night shows this star is superhumping.
Amplitude is 0.2 magnitudes, and a crude period analysis gives 0.109
days, or 2.61 hours.

Tom Krajci
Cloudcroft, New Mexico

-- 
-------------------------------------------
Tom Krajci
Cloudcroft, New Mexico
http://picasaweb.google.com/tom.krajci
<http://picasaweb.google.com/tom.krajci>

http://overton2.tamu.edu/aset/krajci/
<http://overton2.tamu.edu/aset/krajci/>



From jop at astro.columbia.edu  Thu Jun  5 15:49:09 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Thu, 05 Jun 2008 15:49:09 -0400
Subject: (cba:news) V2491 Cyg
Message-ID: <48484335.5030101@astro.columbia.edu>


Dear CBAers,

There's quite an interesting new nova in the morning sky this month (and 
last): V2491 Cyg, at 19h 43m 2.1s +32d 19m 12.8s.  It has become a 
supersoft source, and my guess is that it's powering a nice orbital 
signal around now (or perhaps in a few weeks)... from reprocessing in 
the atmosphere of the orbiting secondary.  Let's have a look and see!
A few nights of light curve will suffice... and if the answer's no, try 
again in a month.  Nice experiment - the WD-facing hemisphere of the 
secondary acts as a "bolometer" for the hot WD.

GW Lib and SDSS1627+12 continue to be excellent targets, too!

joe


From jop at astro.columbia.edu  Thu Jun  5 15:58:28 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Thu, 05 Jun 2008 15:58:28 -0400
Subject: (cba:news) v2491 cyg, redux
Message-ID: <48484564.60901@astro.columbia.edu>


I think V2491 Cyg is around 14th mag now - but have a look and see. The 
color is pretty red (from interstellar absorption), and so you could 
consider a red filter.  When it gets much fainter, you'll be driven to 
unfiltered observation... and it's even possible that's required now.
As usual, our interest is the TIME SERIES (to study for periodic 
signals) - but if you do use a standard filter, observe a standard star 
so we can calibrate the observation.

Good luck with this one!

joe


From jop at astro.columbia.edu  Thu Jun  5 23:45:02 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Thu, 05 Jun 2008 23:45:02 -0400
Subject: (cba:news) GW Lib 'round the clock...
Message-ID: <4848B2BE.5040103@astro.columbia.edu>


Dear CBAers,

We've been tracking GW Lib faithfully for the last month, mainly 
following the mysterious 2.0 hr photometric signal.  The coverage has 
been very good, thanks mainly to Bob Rea, Berto, and Tom Krajci.  Our 
data seems to show that the true period is 4.1 hr (2.0 hr is merely a 
powerful first harmonic).  That's interesting.  But something vastly 
more interesting happened two nights ago.  In a space of half a day, a 
very powerful (0.07 mag) periodic signal at 1187 s jumped up from 
nowhere... and has persisted in 3 nights of observation (from Bob Rea 
and Greg Bolt).

This vaults GW Lib to an absolute top priority target.  Fire away with 
all available weapons!

joe


From jop at astro.columbia.edu  Fri Jun  6 00:27:14 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Fri, 06 Jun 2008 00:27:14 -0400
Subject: (cba:news) GW Lib comp star
Message-ID: <4848BCA2.9080804@astro.columbia.edu>


By the way, I recommend GSC 6766-1622 as a comp star for GW Lib.  As you 
all know, we're not finicky about comp stars - but this is one is well 
situated and we have a solid baseline of data with which to merge new 
photometric data.

Take data once a minute or faster.  To study the full power spectrum, we 
need to take data fast enough to resolve any periods which might 
plausibly be present.  It is possible that there are yet faster signals 
in GW Lib.

Oh, and if possible to record airmass in your time series (in addition 
to JD and delta mag), then do so.  That'll allow me to conveniently make 
a first-order correction for differential extinction.


joe


From jop at astro.columbia.edu  Sun Jun 15 13:45:09 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sun, 15 Jun 2008 13:45:09 -0400
Subject: (cba:news) stars for mid-June
Message-ID: <48555525.5020803@astro.columbia.edu>


Dear CBAers,

The Junebugs are out, olde whiteface is back, and it's time to roll the 
target stars.

1. GW Lib has been a treasure trove! I've learned a lot about the 
mysterious 2.1 hr variation:

* it's actually a 4.2 hr signal;
* it's a poor clock, wandering in phase over a few days;
* its amplitude is highly variable on a timescale of a few days, and
   possibly varies in (anti)sync with the amplitude of the 20 min
   pulsation.

And the star shows a rich pulsation spectrum - not much correlated with 
the signals present prior to the outburst.

It's a great star and beautifully placed for all australites, except a 
few days (like now) each month.  I'm sure it will continue to be very 
rewarding for at least another month.

2. Late in these southern winter nights, V1432 Aql and CD Ind are very 
attractive targets.  These are 2 of the 5 known "BY Cam stars", in which 
a slowly rotating white dwarf gradually synchronizes with the orbit. 
We're in a privileged position to watch this synchronization - so let's 
do it!

As for northern targets:

1. Delete MV Lyr.  I'm still not sure if the orbital signal showed up in 
the last month's coverage.  If so, it was too weak to do much with. 
I'll finish the analysis when I get back from Italy.  But for the rest 
of 08, let's ditch it.

2. SDSS1627+12.  Nice dwarf nova outburst, nicely covered.  Seems to be 
back down though... so that seems to be the end.

3. V2491 Cyg.  Worth a try... but Bob Koff got 5 straight nights, and no 
periodic signals appeared.  This star is apparently not yet inclined to 
yield its secrets.  Maybe in the (northern) fall, or next year.

4. GW Lib.  If you're decently southern and not too bothered by 
moonlight, please do this star.  The USA especially fills in the ZA-NZ 
gap, and global coverage is VERY DESIRABLE to track these complex 
signals.  If you explicitly show airmass (in a third column, say), then 
I can make an airmass correction - up to about 2.8 airmasses.  (Beyond 
2.8 airmasses, I wouldn't recommend going; I susually say 2.2, but I'm 
greedy here.)

5. RX1813+61 = Dra.  Very handsome negative superhumper, nicely placed 
in the sky.

Plus two equatorial stars:  RX1730-05 and V1494 Aql.  The former has a 
very fast periodic signal; see if you can 20 s time resolution or 
better.  The latter has a 3.5 hr wave that looks different every year, 
as the hot white dwarf cools. Let's find out what it looks like this year!

I'm off to Italy for about 10 days.  I hope to find some email 
connectivity;  the chance of reading email is probably good... the 
chance of replying (except maybe in monosyllables) not quite as good. 
But this is a good menu - and Jonathan can handle any CBA biz.

joe


From jop at astro.columbia.edu  Sun Jun 29 22:04:13 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sun, 29 Jun 2008 22:04:13 -0400
Subject: (cba:news) VY Aqr erupts...
Message-ID: <48683F1D.4080808@astro.columbia.edu>


Dear CBAers,

It seems likely that VY Aqr has just jumped to 10 th magnitude... and 
this suggests a probable superoutburst - and possibly the first day of 
it, too!  This equatorial target is available to everyone, so it's very 
attractive for a round-the-world campaign.  Train your best firepower on it.

But don't forget GW Lib!  The present campaign is going great, and the 
documentary record of both the fast pulsations and the "2-hour" signal 
is one of our best ever.

At tenth magnitude, you may well choose to use a filter (V is usually 
the best choice) since it allows calibration and better treatment of 
extinction.  It would be desirable - though certainly not necessary - to 
attach a third column giving the airmass.  This will enable some extra 
corrections for differential extinction.

When you first visit the field, select an appropriate comparison star, 
and send details to cba-news.  Other observers may well choose to use 
the same comp; that also allows for somewhat easier splicing of the 
light curves.

joe


From jop at astro.columbia.edu  Mon Jun 30 05:48:42 2008
From: jop at astro.columbia.edu (Joe Patterson)
Date: Mon, 30 Jun 2008 05:48:42 -0400
Subject: (cba:news) VY Aqr erupts...
In-Reply-To: <4868B5FF.64CE.0046.0@nmisa.org>
References: <48683F1D.4080808@astro.columbia.edu>
	<4868B5FF.64CE.0046.0@nmisa.org>
Message-ID: <4868ABFA.7070404@astro.columbia.edu>



Hi Berto et al.,

Yeah, CD Ind is a long-term project, following the synchronization of 
that wayward white dwarf.  Your early-season data specifies the phase 
pretty well; a rush of late-season data, and a couple of mid-season 
points sprinkled in there, will do the job nicely.  But VY Aqr in a July 
superoutburst, now that's just too delicious to resist... or even to be 
restrained about.

Thanks for the calibration homework.

joe



> 
> The following comparison stars (for C or K) can be adviced. 
> 
> With Loneos photometry:
> 
> VY Aqr 15          21 12 10.2   -08 49 03   h 5772-0390  13.91   0.86   0.54        
> VY Aqr 16          21 12 11.2   -08 49 59   h 5772-0074  13.82   0.75   0.42        
> VY Aqr 1v          21 12 11.3   -08 53 08   G 5772-0143  10.97   0.55               
> 
>>From the latter we can derive an R magnitude of 10.65 for unfiltered reference. For the others subtract the third column values (V-R) from the first column (which is V).
> 
> Good luck to the campaign!
> 
> Berto Monard / CBA Pretoria
> 
>  
>