PNV J20233073+2046041 mag 6.8

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Re: PNV J20233073+2046041 mag 6.8

Postby Christian Buil » Thu Aug 29, 2013 10:58 pm

Paolo,

Your spectrum is exceptional. And what a job!
Can you precise the exposure time for the 7 slices?
And the time for calibrate...

Quelle patience et quel talent !

A beautifull use of Lhires III and his great potential. This is
a real lesson to many observers, I am sure.

Yes it is a very powerful infrared spectrograph
(see also my tests concerning the infrared triplet Ca II in
the perspective of GAIA mission). It is even possible to
improve it by using a 600 l/ mm grating blazed to 7500 A.

Christian
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Re: PNV J20233073+2046041 mag 6.8

Postby Paolo Berardi » Fri Aug 30, 2013 9:42 am

Christian, thanks very much for your encouraging words!
Fortunately the target is very bright and I've worked with "co-pilot" Giuseppe!

Concerning data reduction I firmly believe that the increased efficiency is due to ISIS pipeline. I created several files (spectral calibration file mode) for each interval using Ne and Ar lines, so I'm ready to switch beetween different spectral domain. After first reduction, XML recall function prepares almost all parameters with a mouse click... Great, I always use it!

Following timing, approximate ranges and exposure for 28 august spectra:

28.804 aug: UV (3750-4200, cropped), 16 x 90 s
28.837 aug: BLUE-GREEN (4200-5100), 10 x 90 s
28.854 aug: GREEN-YELLOW (5100-6100), 10 x 90 s
28.872 aug: RED (6000-7000), 14 x 45 s
28.902 aug: IR part 1 (7000-8000), 10 x 90 s
28.921 aug: IR part 2 (7800-8800), 10 x 120 s
28.954 aug: IR part 3 (8600-9500), 15 x 120 s

Note I used the new 30 micron slit (it seems to me a very good compromise beetween throughput and resolution with my telescope).

Very interesting the 7500A blazed grating...

Ciao!
Paolo
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Re: PNV J20233073+2046041 mag 6.8

Postby Robin Leadbeater » Fri Aug 30, 2013 12:10 pm

Hi Paolo,

That is very impressive going so far into the IR. It is even possible to go a small distance into the IR using the LHIRES at high resolution with the 2400 l/mm grating but this needed some surgery on the grating holder :shock:
http://www.threehillsobservatory.co.uk/ ... opy_13.htm

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: PNV J20233073+2046041 mag 6.8

Postby Christian Buil » Fri Aug 30, 2013 2:10 pm

Here my version of full Vis + IR spectrum of nova taken with Alpy 600 spectrograph and 200 mm tel. :

Voici ma version d'un spectre complet VISIBLE + INFRAROUGE pris avec un spectrographe Alpy 600 et le
télescope de 200 mm :


Image

Taken in two part : Visible (20 x 50 sec exposure, 18 microns slit) from 3650 A to 7200 A and
IR (20 x 50 sec., 18 microns slit) from 6000 to 8735 A). Thanks to large detecteur of Aik460EX.
The spectrum is captured with noting moving part (but the spectral résolution up to 7800 A
is degraded, evaluated to R = 500).

Fait en deux parties, avec à chaque fois 20 poses de 50 secondes (la nova demeure brillante pour ce
type de configuration). J'ai utilisé unne fente de 18 microns.


Compare with the Paolo and Giusseppe more resolved spectrum.

A comparer avec le spectre plus résolu de Paolo et Gisusseppe fait hier.

For capture the IR part I have added an order filter just in from the spectrograph (attached with some
adhesive..., but it is functionnal, the most important !) :

Pour saisir la partie IR j'ai utilisé un filtre d'ordre (couleur orange, type équivalent WR42).
Il est juste à l'avant du spectro, c'est un peu bricolé avec de l'adhésif, mais cela fonctionne,
c'est l'essentiel :


Image

It is the first tentative of IR observation of a celestial object with Alpy600 (out of specification,
but it work on bright objects).

C'est ma premier tentative IR sur le ciel avec Alpy600 (j'avais déjà fait
des végétaux, mais c'est autre chose). Un peu hors spécification du spectrographe Alpy, mais
ca donne tout de même quelque chose (attention, grand capteur indispensable, ici une caméra Atik460EX).


Christian
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Re: PNV J20233073+2046041 mag 6.8

Postby Christian Buil » Fri Aug 30, 2013 6:17 pm

Here the classic BVRI Bessel filter transmission

Image

Now the product of August 29.8 Alpy spectrum and the filters transmission:

Image

For the classical photometry we integrate the signal of each spectral band. This give raw BVRI magnitude.
But photometry fails to explain the complex phenomena of a nova.

(By curiosity from my data, the computed color index (only from flux measure, not attached to a photometric system):
B-V = -0.66
B-R = +0.18)


A better solution, display the spectrum in physical flux unit (ergs/cm2/s/A for example).

For this use if possible a wide slit (here the Alpy 600 photometric slit - 180 microns):

Image

The intensity in count unit is measured for the reference star HD196544 and for the nova,
then, the real flux of the nova is computed (the conversion is trivial):

Image

It is still richer than conventional photometry!

Christian
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Re: PNV J20233073+2046041 mag 6.8

Postby Ernst Pollmann » Fri Aug 30, 2013 8:09 pm

I am still working on the line flux analysis.
Is there someone, who took series of Halpha spectra on August 15/16/17?
Brightness monitorings during these three nights of U. Schmidt (BAV, see attachment) enable to study the inverse correlation of Vmag and Halpha EW in detail.
That this kind of correlation does exist is shown in the attached plot (Vmag_EW).

Ernst Pollmann
----------------------------------------
Active Spectroscopy in Astronomy
http://www.astrospectroscopy.de
http://www.astronomie.de/astronomische-fachgebiete
Attachments
Vmag_16-17-18.jpg
Vmag_16-17-18.jpg (92.03 KiB) Viewed 3867 times
Vmag_EW.jpg
Vmag_EW.jpg (42.78 KiB) Viewed 3867 times
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Re: PNV J20233073+2046041 mag 6.8

Postby Francois Teyssier » Fri Aug 30, 2013 8:40 pm

V band photometry
30-08-2013 20:28
V = 6.80 +/0.01

novadel-phot.PNG
novadel-phot.PNG (178.31 KiB) Viewed 3862 times
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Re: PNV J20233073+2046041 mag 6.8

Postby Francois Teyssier » Fri Aug 30, 2013 9:49 pm

Calibration en flux absolu avec la méthode "basique"
V = 6.80 (Johnson V)
Je multiplie le spectre en intensité relative par la courbe de réponse du filtre Vert Johnson
Puis je calcule le rapport de l'aire se trouvant sous le continuum sur l'aire totale (feuille excel, à améliorer)
Cela donne un coefficient multiplicateur (environ 0.85) qui corrige le flux des raies et permet de retrouvrer la valeur absolue du continuum à 5500 A
Ensuite, transformation classique de la mag V en flux absolu à 5500

novadel_flux.PNG
novadel_flux.PNG (13.47 KiB) Viewed 3853 times



Pour Ha, cela donne F = 7.9E-9 erg/cm2/s

François
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Re: PNV J20233073+2046041 mag 6.8

Postby Christian Buil » Sat Aug 31, 2013 2:04 am

Francois, tu trouve une valeur très proche de celle que j'ai donnée hier j'ai l'impression (j'ai refait une mesure cette nuit, on va pouvoir comparer à nouveau).
La difficulté est de trouver le facteur 0.85 j'ai l'impression ? Ajustement d'un continuum approximatif ? Faut aussi passer par une évaluation de la magnitude V.
Ce sera interessent de mettre les méthodes en parallèles. Ce soir cela m'a pris 10 minutes pour faire l'étalonnage en flux (le temps de pointer la nova puis la référence
(dont on connais déjà V), puis 2 x 60 s de poses, le calcul se limite ensuite à une régle de trois - en gros).

Serait bien de mettre les procédures sous forme de diagrammes pour bien montrer la logique. Je vais tacher de faire cela pour la méthode spectrophotométrique.

Christian
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Re: PNV J20233073+2046041 mag 6.8

Postby Christian Buil » Sat Aug 31, 2013 2:08 am

Evolution rapide du spectre vers 5300 A (fort décalage Doppler d'un jour à l'autre) :

Image

Olivier G, va falloir vérifier avec tes données eShel (comme quoi, la redondance de données
n'est jamais une perte de temps).

Evolution entre hier et aujourd'hui de Halpha :

Image

Christian
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