PNV J20233073+2046041 mag 6.8

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Christian Buil
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Re: PNV J20233073+2046041 mag 6.8

Post by Christian Buil »

[English] (version française à la fin)

Nova is currently very stable in magnitude
and the spectrum is virtually unchanged between
August 4.9 and August 5.9 at intermediate resolution.

This is what shows the Alpy 600 flux calibrated spectra below.
Note the good spectrophotometric
quality achieved (high signal to noise ratio, ...). Note also that
these spectra are calibrated in absolute flux, not in
relative intensities. See details here:

http://www.astrosurf.com/buil/nova_del2 ... ometry.htm

Image

Image

The next graph shows tevolution of V magnitude in 6 days:

Image

The plateau phase arrival is clear. These data are extracted from
spectra only – not images with a V filter or a photometer.
I use here numerical passband filters.

I think in a day or two make a connection with the BVR
Johnson system (I have measured some Landolt standards).

This document is a first for me and I think it opens
a new area for amateurs - a new approach of
photometry (and spectroscopy). This is a door
for more numerous pro/am collaborations.

==================================================

[Français]

La nova est actuellement très stable en
magnitude et le spectre est virtuellement inchangé
entre le 4.9 août et le 5.9 août (pour des résolutions
spectrales intermédiaires).

Les spectres Alpy 600 présenés sont étalonnés
Remarquez la très bonne qualité spectrophotometrique
atteinte (fort rapport signal sur bruit, ...). Notez bien que ces spectres
sont étalonnés en flux absolu, pas en intensités relatives.
Voir les détails ici:

http://www.astrosurf.com/buil/nova_del2 ... ometry.htm

Un graphe montre aussi l'évolution de la magnitude V en 6 jours. On voit
bien arriver la phase plateau. Ces données sont issues de
spectres uniquement, pas de mesures faites avec des images
prises avec un filtre V ou avec un photomètre. J’utilise
ici des filtres passe-bande numériques. La mesure est faite
sur les spectres par calcul.

Je pense, dans un ou deux jours, pouvoir faire un rattachement
avec le système BVR Johnson (j’ai fait aussi quelques étalons
Landolt).

Ce document est une première moi et je crois que ce type de
mesures une nouvelle aire pour les amateurs - une
nouvelle approche de la photométrie (et de la
spectrographie). C'est une porte pour des collaborations
pro/am plus nombreuses encore.

Christian B
Robin Leadbeater
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Re: PNV J20233073+2046041 mag 6.8

Post by Robin Leadbeater »

An update of my calculations of H alpha line strength (absolute flux, arbitrary units, click on the attachment to see the trend graphs)
The spectra are low resolution (LISA and ALPY) from the database and scaled to the continuum at H alpha
The H alpha EW is then converted to absolute flux (arbitrary units) using the AAVSO Vmag values (Flux = EW/10^0.4Vmag)
These values are then individually corrected for the ratio of the weighted mean flux in the Vmag passband to that in the continuum at the H alpha line.
(The weighted mean in the Vmag passband is calculated by multiplying the spectra by the normalised Bessel V response and calculating the mean of the result)

Cheers
Robin
Attachments
Novadel2013_Halpha_flux.png
Novadel2013_Halpha_flux.png (11.79 KiB) Viewed 6996 times
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Christian Buil
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Re: PNV J20233073+2046041 mag 6.8

Post by Christian Buil »

Excellent analysis Robin and very informative.

We are all coherent. For the present time the continuum absolute flux is relatively stable.

At the same time the Halpha intensity relative to continuum increase slightly, see comparison
of my two lastest eshel spectra:

Image

(telluric lines are removed - only for the presentation)

Christian
Olivier GARDE
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Location: Rhône Alpes FRANCE
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Re: PNV J20233073+2046041 mag 6.8

Post by Olivier GARDE »

Same graph as Christian (at the same time) but with telluric lines
Image
LHIRES III #5, LISA, e-Shel, C14, RC400 Astrosib, AP1600
http://o.garde.free.fr/astro/Spectro1/Bienvenue.html
Olivier GARDE
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Re: PNV J20233073+2046041 mag 6.8

Post by Olivier GARDE »

And a graph to show the evolution of the nova from the 14th august (just some few hours after his discovery) and the 5th september.

Image
LHIRES III #5, LISA, e-Shel, C14, RC400 Astrosib, AP1600
http://o.garde.free.fr/astro/Spectro1/Bienvenue.html
Jacques Montier
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Joined: Sun May 13, 2012 2:46 pm

Re: PNV J20233073+2046041 mag 6.8

Post by Jacques Montier »

Christian Buil wrote:Ben c'est assez simple Jacques. Tu a bonne résolution de la résolution si tu traite ton spectre de néon de référence.
Tu fait exactement comme pour l'étoie, mais là pour, tu ne demande pas de retirer le fond de ciel (!).
Coche aussi la jsute au dessus de demandant pas de corriger la coordonnée Y des spectres
(pense à remettre tout en ordre pour traiter des étoiles ensuite). Change rien d'autre.

Tu traite de manière standard. Tu va obtenir un spectre en émission. Avec l'outil FWHM tu peux
mesurer la résolution pour finir (le FWHM en angstroms d'abord, puis R = lambda / FWHM).

Pas plus dur et c'est LA methode.

Christian
Merci Christian, je fonce essayer tout ça ! ;)
--
Jacques Montier
Societe d'Astronomie de Rennes
IAU code J23
Christian Buil
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Re: PNV J20233073+2046041 mag 6.8

Post by Christian Buil »

Jacques, noter que cette importante méthode pour déduire la résolution spectrale
est décrite en bas de la page :

The method for compute the spectral resolution at the hand is described
at the end of page:


http://www.astrosurf.com/buil/isis/guid ... to1_en.htm

(elle existe aussi en français - c'est la base d'usage du Lhires III)

==========

Il n'est vraiment pas commun d'avoir une telle couverture temporaire !
Olivier, c'est vraiment beau la spectro !
Attention, la météo n''est pas bonne du tout pour pas mal d'observateurs en France.
Il faut une mobilisation maximale de tous ceux qui peuvent observer, où qu'ils soient !!!

Incredible spectrographic temporal coverage! Olivier, the spectrography is beautiful !
Warning, waether is not good for many observers in France in particular.
It is the moment to takes a maximum mobilization for all observers in any country.


Christian


Christian
Martin Dubs
Posts: 141
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Location: Maienfeld, Switzerland

Re: PNV J20233073+2046041 mag 6.8

Post by Martin Dubs »

Hello,

I would like to announce that by kind permission of Noel Richardson and Thomas Eversberg from the WR13x-collaboration (see: http://www.stsci.de/wr134/index.htm
and with the help of the observing teams it was made possible to observe the Nova Del 2013 from the IAC80 telescope with an eShel at Teide on 13 nights between aug 17 and sep 5 (weather and equipment permitting some more to come).
The results have been uploaded to the ARAS database under the name WRx-collaboration. The thin dry air is especially useful for the observation of H-alpha lineshape. Of course the main goal is still the observation of WR stars, so only a limited time could be used for the observation of the nova.
To give an idea of the spectra obtained there the last example from sep 5,
merged spectrum, black linear scale left axis, red log scale right axis
merged spectrum, black linear scale left axis, red log scale right axis
_novadel2013_20130905_950_full.png (12.94 KiB) Viewed 6971 times
with an aditional plot for the comparison of H-alpha and H-beta from the same spectrum (O34 and O46) on a velocity scale, normalized to the peak height:
H-alpha and H-beta displayed in radial velocity
H-alpha and H-beta displayed in radial velocity
_novadel2013_20130905_950 velocity.png (8.83 KiB) Viewed 6971 times
Noticeable is the double peak and the different linewidth.
This profile reminds me of quite similar profiles obtained many years ago in a completely different context, the doppler spectroscopy of molecules, in particular the spectroscopy of molecules dissociating after a laser photolysis. In order to get high enough resolution a second tunable laser was used with a narrow linewidth. The difference to the above spectrum is the range of observed doppler widths, m/sec instead of km/sec, the observed volume: a mm^3 of low pressure gas instead of a solar mass and the possibility to observe the reaction from different angles with different lineshapes depending on laser polarization and viewing angle:
Doppler velocity profiles of laser induced photofragments viewed from different angles
Doppler velocity profiles of laser induced photofragments viewed from different angles
NO doppler velocity.jpg (117.4 KiB) Viewed 6971 times
abstract: http://jcp.aip.org/resource/1/jcpsa6/v84/i6/p3106_s1
I know this is a bit off topic, but interesting that in physics the same problems occur in quite different fields, from tiny molecules to astrophysics.

Regards, Martin
Francois Teyssier
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Re: PNV J20233073+2046041 mag 6.8

Post by Francois Teyssier »

Robin Leadbeater wrote:An update of my calculations of H alpha line strength (absolute flux, arbitrary units, click on the attachment to see the trend graphs)
The spectra are low resolution (LISA and ALPY) from the database and scaled to the continuum at H alpha
The H alpha EW is then converted to absolute flux (arbitrary units) using the AAVSO Vmag values (Flux = EW/10^0.4Vmag)
These values are then individually corrected for the ratio of the weighted mean flux in the Vmag passband to that in the continuum at the H alpha line.
(The weighted mean in the Vmag passband is calculated by multiplying the spectra by the normalised Bessel V response and calculating the mean of the result)

Cheers
Robin
Good work Rob in !
Could you compute the absolute flux ?

François
Martin Dubs
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Joined: Fri Jan 06, 2012 9:16 pm
Location: Maienfeld, Switzerland

Re: PNV J20233073+2046041 mag 6.8

Post by Martin Dubs »

Hello Francois and Robin,

the calibration constant for conversion to absolute flux can be obtained by applying the same procedure to e.g. a Vega spectrum. The flux for a V = 0 star at 5450 A is:
flux Vega.jpg
flux Vega.jpg (30.58 KiB) Viewed 6968 times
from a reference which can be found by Google with "ASTR 511 magnitude color virginia"
The calibration constanrt can be determined to give the desired absolute flux for Vega based on the equation:
vegamag.JPG
vegamag.JPG (92.74 KiB) Viewed 6968 times
from the same reference.
So instead of using two measured spectra for the absolute calibration as Christian does it, one can use one spectrum and the V mag plus a calibration constant from a spectrum with absolute calibration.
I wanted to do this after a suggestion to Ernst but was busy with the Teide spectra and now Robin has done already 99% of it!
Would be interesting to see if you get the same results as Christian.

Regards, Martin
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