PNV J20233073+2046041 mag 6.8

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Re: PNV J20233073+2046041 mag 6.8

Postby Olivier Thizy » Sun Aug 18, 2013 9:14 pm

Fifth night on the nova... weather has never been so nice with me this year! :-)

Here is my first serie of tonight:
_novadel2013_20130818_804_OThizy.jpg
_novadel2013_20130818_804_OThizy.jpg (60.82 KiB) Viewed 5256 times



Changes are well visible in Halpha for exemple!
_novadel2013_20130818_804-20130818_032.jpg
_novadel2013_20130818_804-20130818_032.jpg (55.08 KiB) Viewed 5256 times



And another picture of the temporary setup at home: Televue 85mm, NEQ6 mount, Alpy 600 spectrograph with Atik Titan & Atik 460ex...
web_IMG_7159 Olivier & Alpy600.jpg
web_IMG_7159 Olivier & Alpy600.jpg (249.11 KiB) Viewed 5256 times



Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/
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Re: PNV J20233073+2046041 mag 6.8

Postby Olivier GARDE » Sun Aug 18, 2013 9:56 pm

Evolution of HAlpha line since 24H.
In blue, the spectra taken yesterday
In red, the spectra taken just now.
Notice, that the Halpha line increase in emission and the part of HAlpha in absorption decrease.
Image
LHIRES III #5, LISA, e-Shel, C14, RC400 Astrosib, AP1600
http://o.garde.free.fr/astro/Spectro1/Bienvenue.html
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Re: PNV J20233073+2046041 mag 6.8

Postby Olivier Thizy » Sun Aug 18, 2013 10:13 pm

Hello,


clouds are coming in so I have to give up observations tonight... Too bad as even between two exposures taken 1h40m apart tonight, I was able to see the change in Halpha which is happening at the moment: the emission is growing and Hlpha is now the brightest spot of my raw spectrum (was around Hbeta before)...

_novadel2013_20130818_804-874.jpg
_novadel2013_20130818_804-874.jpg (52.25 KiB) Viewed 5245 times



Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/
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Re: PNV J20233073+2046041 mag 6.8

Postby Keith Graham » Sun Aug 18, 2013 10:26 pm

Hi Olivier,

I installed Gnuplot per your instructions and Christian's Install link. All went very well up until the very last step.

For a reason I do not understand, when I click the Plot button in the Free Plot box, I get the following message in the lower right white box:

Write : c:\aaaspecwd\novadel2013.png
Ok.


So ISIS says it is writing a png file to my working directory, but there is no png file there. Instead there is only a @ dat file.

I did fill in all of the boxes that you filled in your screenshot you sent. I also downloaded and placed in gnuplot folder the 3 std.gnu files. Their notepad readouts are identical to the ones in Christian's document. Any idea what I may be missing?

Cheers,

Keith
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Re: PNV J20233073+2046041 mag 6.8

Postby Martin Dubs » Sun Aug 18, 2013 11:42 pm

Hi Keith,

So ISIS says it is writing a png file to my working directory, but there is no png file there. Instead there is only a @ dat file.

maybe this comment can help you:
http://www.spectro-aras.com/forum/viewtopic.php?f=8&t=532&p=1887&hilit=gnuplot#p1887
the same problem here:
http://www.spectro-aras.com/forum/viewtopic.php?f=8&t=515&p=1830&hilit=gnuplot#p1830

Look also at the file "gnuplot.txt" in your gnuplot directory. That may give you an additional hint.

Regards, Martin
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Re: PNV J20233073+2046041 mag 6.8

Postby Olivier Thizy » Mon Aug 19, 2013 7:25 am

Hello,


here is a comment on the Radial Velocity of the nova:


The terminal velocity of the line profile is an absolute thing,
relative to the rest wavelength, not the separation of maximum and
minimum (you see that described, too often, in the older photographic
literature). So you're right in saying that there's been a change but
it's mainly in the shape and minimum of the absorption. You'll notice
that in the last profile the absorption has changed shape, this is the
sort of thing some models predict for the evolution as the ejecta
expand since the different layers have different temperatures and
densities along with different velocities. You never see this sort of
thing in winds unless they're very collimated (and that's rare enough).
Instead, the decrease is when the line is formed deeper in. Remember,
this was very hot and not that it's cooling the optical is becoming
less opaque. This is a part of the spectrum where there are few
absorbers, the main opacity sources are scattering and thermal (and the
photosphere down to which you're seeing -- or rather a moving opaque
surface). The timescale for the changes is consistent with the column
density varying as 1/t^2 and the optical depth varying as 1/t. So you
would expect that (since the intensity depends on the exponential of
the optical depth) that the line intensity at any velocity should vary
as

I(vel) ~1- exp [- (t0/t)]

where the time t0 is a scaling time. In other words, as the expansion
causes the opacity to drop the intensity at a given velocity increases
(decreased absorption). This will go on for a bit until the Fe lines
appear, as they seem to be now starting to do.

Steve Shore



in reply to:

François Teyssier wrote:
> Dear Steve,
>
> Keith Graham, an observer of the campaign, raises a question about
> measurement of the velocity of the ejecta, from the difference between
> P cygni absorption and the emission
> He computes a decreasing of about 200 km/s in one day.
> Obviously, the P Cygni absorption is fading, that produces the
> displacment of its maximum to the red.
> Is it a measure of a real decrease of the expension velocity, or a
> bias due to the evolution of the P Cyg profile ?
>
> François
>
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Re: PNV J20233073+2046041 mag 6.8

Postby Olivier Thizy » Mon Aug 19, 2013 7:35 am

How bright will remain the nova? I asked the question to Steve Shore - well, prediction are not that easy... but here is his answer:

As a first guess, if this is like others of the class there will be
± 1 mag excursions that may seem weird but they won't last more than
a few days.

The nova -- if a DQ Her type object -- will likely stay at
a similar level for the next two months. The critical period will be
the next week or so, for the molecular lines and the passage to the deep
absorption. Whatever cadence people can get is what we get, the
collective effort will guarantee that this is the best covered nova in
history -- in fact, it already is!

PLEASE let everyone know how much their efforts are appreciated and
that there will be more notes coming (also on some general issues of
spectroscopy, OK? I'd promised that some time back).

Steve



As Steve points out, it is key to continue to observe as frequently as possible at multiple wavelength. Our spectra are very important as this is the first time coverage of this magnitude for a nova. This is rather unique and the nova seems also a strange one (well, I'm not a specialist there...just reporting what I'm beeing told!).

The changes in the absorption velocities mean the
absorption is formed progressively deeper (lower velocities) while the
fraction filling the space that's transparent -- that produces the
emission -- is relatively increasing. You'll see this comparing the
Balmer profiles. One thing that may help with visualizing is to plot
things in velocity, from -4000 to 4000 km/s with rest wavelengths of
6562.7 and 4861.4 (air). These will make the comparisons between the
profiles at the same time simpler. The most intriguing part of the
spectrum, aside from the Na I region, seems now to be the 4200 A
region.

Steve



Beeing several observers and having the time coverage is key:

KEEP GOING!!! Wonderful stuff, you're producing data that even the professional observers are not able to get!



Thank you to all observers... Analysis is currently quickly done. It will take months (years?) to analyse all the data we are producing... and it is critical to acquire the data now as it is changing rapidely!


Reminder: send your spectra in FITS file format to be included in ARAS database?
1/ reduce your data into BeSS file format
2/ name your file with: _novadel2013_yyyymmdd_hhh_Observer
novadel2013: name of the nova, fixed forthis object
yyyy: year
mm: month
dd: day
hhh: fraction of the day, beginning of the observation
Observer: your pseudo/name
Exemple: _chcyg_20130802_886_toto.fit
3/ send you spectra to François Teyssier to be included in the ARAS database visible here:
http://www.astrosurf.com/aras/Aras_DataBase/Novae/Nova-Del-2013.htm



Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/
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Re: PNV J20233073+2046041 mag 6.8

Postby Olivier Thizy » Mon Aug 19, 2013 12:07 pm

Hello,


Below is an important note from Steve Shore encouraging you to continue to observe as much as possible; changes are rapid and need close spectroscopical monitoring. Keep up with your observations!

-------------------------------

This is VERY important, Olivier! The Fe II is now starting to show the
narrow features -- it's recombining (almost on schedule) and now please
let people know that every day counts.

There will be structure (multiple components in absorption) on all of
the newly appeared metallic ion lines (e.g. Fe II and also forbidden
lines). The current velocities are almost 1000 km/s but these will
change over time (there's a section of the BASI paper that describes
some of this but I should write more in the next day as notes for you
all).

We're getting scans of the Stratton and Manning atlas of the DQ Her
1934 event so I may be able to send some files for comparisons (at
least I hope after scanning the spectra can be extracted for line
profiles).

This is just wonderful!

steve

-------------------------------


Here is the current list of observers that have published their spectra on ARAS:
O. Garde : eShel (R=10000) echelle spectrograph, 35cm telescope, France
O. Thizy : Alpy 600 (R=600) spectrograph, 8.5cm telescope, France
T. de France : LISA (R=1000) spectrograph, 23cm telecope, France
D. Antao : Alpy 600 (R=600) spectrograph, 25cm telescope, France
J. Edlin : LISA (R=1000) spectrograph, 20cm telescope, USA
K. Graham : Alpy 600 (R=600) spectrograph, 25cm telescope, USA
J. Guarro : home made (R=6500) spectrograph, 40cm telescope, Spain
F. Teyssier : LISA (R=1000) spectrograph, 25cm telescope, France
P. Berardi : Lhires III/600 (R=2500) spectrograph, 23cm telescope, Italy
T. Bohlsen : LISA (R=1000) spectrograph, 28cm telescope, Australia
E. Pollmann : Lhires III/2400 (R=15000) spectrograph, 35cm telescope, Germany
T. Lemoult : eShel (R=1000) echelle spectrograph, 35cm telescope, France
A. Favaro : Lhires III/2400 (R=14000) spectrograph, 20cm telescope, France
J.-N. Terry : Alpy 600 (R=600) spectrograph, 25cm telescope, France

I'm glad that 14 different people have submitted their spectra to ARAS / François Teyssier. I know several of you are working on their processing to be included in the database, so the list of names will increase. Of course, do not hesitate to ask if you need any help. It would be very nice to get more people from US & Australia time zone for better time coverage... :-)


The nova brightness is doing an halt after maximum which is very rare... so this seems to be a unique object which is worth observing on a continuous basis at the moment and for at least one week...


Cordialement,
Olivier Thizy
Vous ne verrez plus des étoiles comme avant !
http://www.shelyak.com/en/
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Re: PNV J20233073+2046041 mag 6.8

Postby Terry Bohlsen » Mon Aug 19, 2013 1:13 pm

Another spectra tonght from Oz :D
There was passing cloud so I didn't get as long exposure but still it is 20x 30sec.
It has changed a lot in 24 hours and seems to be getting less blue in it's continuum.
Cheers

Terry
Image
Image
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Armidale NSW
Australia
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Re: PNV J20233073+2046041 mag 6.8

Postby Francois Teyssier » Mon Aug 19, 2013 9:25 pm

Spectre du 19-08-2013

Evolution très rapide - le profil P Cygni de H alpha a presque totalement disparu

_novadel2013_20130819_854_fteyssier.png
_novadel2013_20130819_854_fteyssier.png (5.69 KiB) Viewed 5153 times


François
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