From jop at astro.columbia.edu  Sat Mar  1 16:03:29 2014
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sat, 01 Mar 2014 16:03:29 -0500
Subject: (cba:news) msp binaries, candidates, and others
In-Reply-To: <dc21afba44069e2a06a63e6ff5a5792a.squirrel@webmail.astro.columbia.edu>
References: <dc21afba44069e2a06a63e6ff5a5792a.squirrel@webmail.astro.columbia.edu>
Message-ID: <53124B21.9@astro.columbia.edu>

Dear CBAers,

There's a new class of interacting binaries in town.

About ten years ago a few papers were written about a peculiar star, a 
CV-look-alike some of the time.  I attach the one written by Thorstensen 
& Armstrong.  The star turns out to be also a gamma-ray source and 
millisecond pulsar!

There are two other known stars of this type.  One is in M28, not 
readily observable by earthbound telescopes.  The two that can be 
observed are listed below.  They're usually in the range 17-18 mag - no 
picnic - but very little is yet known about the magnitude variations of 
this new type of compact binary.  Outbursts, low states, recurrence 
periods... we're mostly ignorant concerning all these matters - that 
we'd like to know, and that we might well find out.

In addition, there are two other stars that live in quite small Fermi 
error circles, and that have spectra resembling CVs.  Are they CVs?  Are 
they gamma-ray sources, or are they in Fermi error circles by accident? 
  And are they millisecond pulsars?  We don't know any of the answers... 
but we might learn plenty from studying the nightly light curves.

Since this subject is so new, we don't exactly know how to observe these 
stars.  Fast, slow, once a night, long time series... who knows?
The CBA is in a pretty good position to explore this subject.

See what you can find out!  Their charts and positions are attached and 
below.

Re other stars, we're finished with CP Puppis and V745 Sco.  AM CVn is 
going well... and may it continue!  I'm hoping for more action on V406 
Vir - and BK Lyn, too.


joe p

-------- Original Message --------
Return-Path: <jules at astro.columbia.edu>


Millisecond Pulsars/LMXBs in transition

  PSR J1023+0038    10 23 47.6  +00 38 41.0    2000.0
  Chart reference  http://adsabs.harvard.edu/abs/2005AJ....130..759T

  XSS J12270-4859   12 27 58.75 -48 53 42.9    2000.0
  Chart Reference  http://adsabs.harvard.edu/abs/2006A%26A...459...21M



CVs in Fermi Error Circles

  1RXS J083842.1-282723   08 38 43.47 -28 27 01.5    2000.0
  Swift J1544.6-1128      15 44 39.3  -11 28 04.0    2000.0

  Chart reference    none (see attached)
  Spectrum reference http://adsabs.harvard.edu/abs/2013A%26A...559A..58M



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From jop at astro.columbia.edu  Fri Mar  7 10:02:01 2014
From: jop at astro.columbia.edu (Joe Patterson)
Date: Fri, 07 Mar 2014 10:02:01 -0500
Subject: (cba:news) Fwd: (cba:chat) Fwd: [vsnet-alert 16982] SDSS
 J090221.35+381941.9 outburst!
In-Reply-To: <6AD69868-9A1C-46D1-9B26-DBEA8AE7A5BE@gmail.com>
References: <6AD69868-9A1C-46D1-9B26-DBEA8AE7A5BE@gmail.com>
Message-ID: <5319DF69.2010305@astro.columbia.edu>

I'll say!  Glorious new object, and let's fire with all cylinders.  The 
AM CVn outbursts, even the supers, don't usually last long.  Just a 
spectacular new CBA target!

joe

And it's time now to pick up the monitoring of V1159 Ori in the evening 
sky.  In a week the Suzaku observation will start.  We definitely want 
snapshots to cover its wanderings in the 4 d mini-outburst cycle... but 
also time series to monitor for superhumps (the latter applying to the 
Suzaku times mainly, so for now the monitoring is the main thing).




-------- Original Message --------
Return-Path: <cba-chat-bounces at cbastro.org>


  ... And yet another interesting short-period AM CVn-type target found 
in outburst by MASTER.

Enrique


Begin forwarded message:

> From: Denis Denisenko <d.v.denisenko at gmail.com>
> Date: March 6, 2014 8:20:29 PM GMT+01:00
> To: vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp
> Subject: [vsnet-alert 16982] SDSS J090221.35+381941.9 outburst!
>
> MASTER-Kislovodsk has detected this ultra-short period AM CVn-type
> dwarf nova in bright outburst:
>
> SDSS J090221.35+381941.9
>  20140306.748  14.05C  MASTER-Kislovodsk
>  20140306.749  14.08C  MASTER-Kislovodsk
>  20140306.750  14.05C  MASTER-Kislovodsk
>  20140306.773  13.98C  MASTER-Kislovodsk
>  20140306.774  13.97C  MASTER-Kislovodsk
>  20140306.775  14.14C  MASTER-Kislovodsk
>  20140306.796  14.09C  MASTER-Kislovodsk
>  20140306.797  13.97C  MASTER-Kislovodsk
>  20140306.798  13.98C  MASTER-Kislovodsk
>
> Orbital period is 0.03355d (48.3 minutes).
>
> SDSS J090221.35+381941.8
> u=20.16 g=20.23 r=20.47 i=20.58 z=20.76
> http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237657874863948140
>
> Denis Denisenko
> Member of MASTER team at SAI MSU

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From jop at astro.columbia.edu  Wed Mar 12 06:30:16 2014
From: jop at astro.columbia.edu (Joe Patterson)
Date: Wed, 12 Mar 2014 06:30:16 -0400
Subject: (cba:news) (cba:chat) Up and Running---AM CVn
In-Reply-To: <531FB877.9000404@rollinghillsobs.org>
References: <531FB5A1.6070309@centurytel.net>
 <531FB877.9000404@rollinghillsobs.org>
Message-ID: <53203738.7000206@astro.columbia.edu>

Hi Shawn and Jim, and dog-lovers everywhere...

You bet - it's the most prolific periodic-signal producer in captivity! 
  My recollection is that we measured 22 periodic signals in our 
Skillman et al. 1999 study.  At most, maybe 6 of them "are understood".

Now granted, some of the single (non-accreting) pulsating white dwarfs 
have *hundreds* of periodic signals - mostly very close sidebands, only 
resolvable with long time series (esp. by the Whole Earth Telescope). 
But these are actual pulsations of the white dwarf, which has had more 
than a billion years to get its pulsations organized.  AM CVn's signals 
come from the accretion disk, which gas flows through on a timescale of 
days-to-weeks.  So it wins by that yardstick.

A worthy competitor is V455 And (nee HS2331+3905) which has at least 10 
signals, plus one complex at ~5 minutes, which may host dozens of 
components if it could only be resolved.  We may try a campaign to 
resolve it, one of these years.  The first paper ever written on this 
star, by Araujo-Betancor in 2005, is now a classic.  Great star, great 
research, excellent writing.  Helena is now polishing up our first paper 
on this amazing star.

I've been mining CBA data every year to time AM CVn's orbital wave, 
which is very weak at 0.0035 mag semi-amplitude.  We're now finally able 
to see, with a baseline of 36 years (the last 21 from CBA), the period 
change which can test the hypothesis that the star is powered by the 
removal of angular momentum by gravitational waves.  It's a theory 
universally assumed, but not yet tested.  That's the goal - but we need 
a few more weeks of coverage to nail it down, or fail.

HP Lib is another important star of this type, which has received 
surprisingly little attention.  Great target for April through June.

Well, if summer knocks out Shawn, we'll just have to settle for those 
exquisite long light curves we've been seeing from Oregon in recent years.

joe


On 3/11/2014 9:29 PM, Shawn Dvorak wrote:
> Always a good sign when there's no smoke!  I usually shut down my
> observatory during the hot, rainy summer here in Florida and am always
> worried when I hit the power buttons after hauling everything back out
> to the observatory in the fall.
>
> AM CVn's light curve is not the most exciting I've seen but I suppose
> with enough data some periodic signals can be teased out.
>
> Shawn
>
>
> On 03/11/2014 09:17 PM, Jim Jones wrote:
>> After a long, long winter, I powered up the observatory this afternoon
>> and nothing caught on fire.
>>
>> So I will give AM CVn a shot tonight...all night.  But I will be
>> surprised if the wheels don't fall off.
>>
>> Jim Jones
>> ____________________________________________________________
>> Center for Backyard Astrophysics (CBA) mailing lists
>> https://cbastro.org/communications/mailing-lists/
>
> ____________________________________________________________
> Center for Backyard Astrophysics (CBA) mailing lists
> https://cbastro.org/communications/mailing-lists/

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From jop at astro.columbia.edu  Sat Mar 15 01:42:24 2014
From: jop at astro.columbia.edu (Joe Patterson)
Date: Sat, 15 Mar 2014 01:42:24 -0400
Subject: (cba:news) hp lib, cr boo, am cvn, sdss0902+38
Message-ID: <5323E840.8080705@astro.columbia.edu>

Dear CBAers,

It's March again, and practically all the AM CVn stars are up there, 
ripe for observation.  Most importatntly, sdss0902+38 has risen brighter 
than a few days, quite possibly signifying its first-ever superoutburst. 
  Wonderful target - who knows when the next chance will come?

We're getting good coverage on AM CVn, and in a few more weeks we'll be 
able to nail down the long-term Pdot (orbital, that is).  Good target 
for bright, moonlit skies.  And in fact, *so* good that it's time - or 
very soon will be the time - to do the same for HP Lib.  Like AM CVn, it 
will likely be found a source of gravity waves, and to reap that benefit 
we need to know the *precise* orbital period.  Over a long baseline. 
Easy target for all CBA scopes.

I agonize about CR Boo.  We really want to find it faint, or *extremely* 
bright.  It usually ramps up and down rapidly in an intermediate 
brightness state - and periodicity analysis is then quite hampered.  On 
the other hand, if we don't look frequently, we won't find out about its 
luminosity states *or* its periodicities.  So keep an eye on it.

And there are others too.  Major league baseball, Einstein's birthday, 
March madness, the AM CVns... they all come together near the equinox.

joe
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From jop at astro.columbia.edu  Mon Mar 17 10:53:06 2014
From: jop at astro.columbia.edu (Joe Patterson)
Date: Mon, 17 Mar 2014 10:53:06 -0400
Subject: (cba:news) V1159 Ori, SDSS0902+38, etc.
Message-ID: <53270C52.3060208@astro.columbia.edu>


Dear CBAers,

The 5-day Suzaku (X-ray) observation has started, and it would be great 
if you obtained (necessarily) short time series during this week.  And 
if possible, specify your comparison star and its magnitude (we'd like 
it to be calibrated, for a change).

Nothing dramatic may occur, but probably one "echo outburst" will be 
resolved.  That's the main goal of the observation - so finish up the 
V1159 Ori season with a flurry!

SDSS J0902+3819 will probably be the star of the week if it stays 
bright.  Maybe even the star of the year - AM CVn stars are rare, and 
their superoutbursts are mighty hard to catch.

Time to quit on BK Lyn - it seems to be pretty stable this year... in a 
"standstill", to use the Z Cam terminology.  We can also quit on AM CVn 
- the coverage has been so good that all the periods and phases are 
determined very, very precisely.  CR Boo and HP Lib would be worthy 
successors, though.  For some reason (the Galactic pole?), practically 
all the AM CVn stars are in the (northern) springtime sky.

joe
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From jop at astro.columbia.edu  Wed Mar 19 18:19:56 2014
From: jop at astro.columbia.edu (Joe Patterson)
Date: Wed, 19 Mar 2014 18:19:56 -0400
Subject: (cba:news) Fwd: Re: (cba:chat) Next HST observations: SDSS1006+2337
In-Reply-To: <CABkVZH3ipKoHCu0Dkx0p40n41MvyLrxM5WT_XC+-Ug90q5CCxQ@mail.gmail.com>
References: <CABkVZH3ipKoHCu0Dkx0p40n41MvyLrxM5WT_XC+-Ug90q5CCxQ@mail.gmail.com>
Message-ID: <532A180C.7040400@astro.columbia.edu>

Dear CBAers,

Especially the Euros!  We've been clouded out the last 2 nights at MDM. 
  Tonight looks good, but so have the last two, to be quickly followed 
by clouds.  Can you observe this star and send to Boris right away?

joe





-------- Original Message --------
Return-Path: 	<Boris.Gaensicke at warwick.ac.uk>

h=mime-version:in-
X-DSPAM-Signature: 	53293880269276719011667



Dear All,

we are now in the last critical hours, and we have a problem: the
last measurement shows SDSS1006+2337 at V=17.4, which
is much brighter than everything from the last days. It may
simply be a little flickering episode, but it could be the onset
of an outburst.

We will need to get some more data points over the next
~5-6h, otherwise STScI will likely pull the plug on this,
with the loss of 4 HST orbits.

Thanks for any help you can give, and please e-mail
me any observation you can get in addition to
uploading it to the AAVSO data base.

Let's hope it works out right, it's the last target in
the program, and it would be nice to end it on
a positive note.

Best wishes,

Boris




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From jop at astro.columbia.edu  Tue Mar 25 15:48:29 2014
From: jop at astro.columbia.edu (Joe Patterson)
Date: Tue, 25 Mar 2014 15:48:29 -0400
Subject: (cba:news) Fwd: DW UMa, SDSS 0902+38, CR Boo
In-Reply-To: <5331B06C.2070405@astro.columbia.edu>
References: <5331B06C.2070405@astro.columbia.edu>
Message-ID: <5331DD8D.8030801@astro.columbia.edu>



Hi CBAers,

SDSS 0902+38 has been performing beautifully for us... or, from a more
practical viewpoint I guess, you've been performing beautifully for it.
Looks like it may go down as the best observed AM CVn superoutburst
ever.  Still bright, so keep it up!

In 1996 we (actually an earlier generation of CBAers, especially Dave
Skillman, who started the CBA) found some wonderful signals in DW UMa -
a powerful negative superhump and a very powerful nodal precession
signal (at the beat frequency of orbit and superhump).  But it was back
in the floppy-disk era... and with each passing year, that data got less 
and less accessible to me.  I published a brief summary in a 2002 paper, 
and resolved to mount a really wide campaign in a subsequent year.  We 
did, in several years - but the signal disappeared.  A positive 
superhump appeared, which was nice, but a powerful negative superhump, 
TOGETHER WITH THE DEEP ECLIPSE, is a much greater prize since it 
promises to give a diagnostic of how the shape varies with precession 
phase (by watching the eclipse shape change with precession phase).

Enrique tells me that the negative superhump is back!  The season and
declination are great, and it's decently bright too (about 14.7 out of
eclipse).  A great northern target for the next month.

Every few years we run a campaign on CR Boo, the second (or maybe third) 
brightest AM CVn star.  We published a pretty good paper (attached) on 
it back in 1997, but our coverage since then has been kinda fragmentary. 
    The equatorial location (1346+08) means that no one gets long 
runs... and although we have all-longitude coverage in principle, we 
never manage to accomplish it.  Bad weather, bad luck, reluctance of 
southerners to observe a technically-northern star, who knows.  CR Boo 
is especially demanding of almost-round-the-clock coverage, because of 
the rapid cycling (~19 hours).  On the other hand, its relatively short 
stays in the very-bright (13) and very-faint (17) states are much easier 
to analyze and decipher, because one doesn't have to figure out how to 
handle the rapid cycling.

So that all amounts to a fairly complicated story for CR Boo.  But the
time is ripe to start a 2014 campaign - and to sound the alarm if it's
in that very-bright or very-faint state.

And also to continue the HP Lib campaign - on a somewhat lower priority
basis, since it's sort of a April-May-June target, but to get the ball
rolling.

joe


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