Alpy 600 spectrograph - Some results

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Alpy 600 spectrograph - Some results

Postby Christian Buil » Thu Feb 21, 2013 11:42 pm

ALPY 600 is a new spectrograph from Shelyak.

It is an instrument quite different
from the Star Analyser because it is a true slit
spectrograph. You can use extra-wide slit,
intermediate and very narrow slits for peculiar applications
(typically 10 microns). For advanced applications, a
small optional calibration module is available
(with a spectral lamp and a flat-field lamp).

The spectral resolution is near R = 550 with
a 23 microns slit. This is significantly higher
than a Star Analyser and lower than LISA
(R=800-900). The line shape is very uniform for
the spectral range 3700 A - 8000 A (I took care to optimize
the optics (a specific design) for the ultraviolet in particular
because it is of great astrophysical interest).

ALPY 600 can fully accept f/5 optical beam (and of course,
can be used with f/6, f/7,... f/10, ... telescope or refractor).
You can also adapt photographic objective lens!

This is not a multi-object spectrograph as
the Star Analyser, but it captures fainter objects
because the sky background is more dark. I think also it
is a very good spectrograph for spectroscopy of
variable stars, which can effectively replace
standard (U)BVR system. This is a potential fantastic
feature.

The spectrum below is typical of results
obtained with ALPY 600: the spectrum of Seyfert
galaxy NGC4151 captured using the guiding module
(with a 23 microns wide reflective slit). This
module provides a good quality field image (which
is essential for faint object spectrography).
The expsoure time is 20 minutes only. The redshift is
easily measured (a typical educational project!).

Image

As always, I observe in urban conditions ...

Christian Buil
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Re: Alpy 600 spectrograph - Some results

Postby Andrew Smith » Fri Feb 22, 2013 9:33 am

Christian Buil wrote:ALPY 600 is a new spectrograph from Shelyak.

I think also it
is a very good spectrograph for spectroscopy of
variable stars, which can effectively replace
standard (U)BVR system. This is a potential fantastic
feature.


Christian Buil


Christian - The main issue with replacing standard phtometry is that you are in efect doing "all sky photometry" as you image one star at a time, where as with filters and an areal CCD detctor you can do" differential photometry" as you can with a star spectroscope.

As your discusion with Robin on the recent asteroid spectra shows matching the spectra observer to observer is quite difficult even for the leading experts!

I think your new spectrograph and the SA both have a role to play and it is a welcome addition.

Regards Andrew
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Re: Alpy 600 spectrograph - Some results

Postby Christian Buil » Fri Feb 22, 2013 11:22 am

Andrew, your are right, the universal spectrograpgh is unknow and
Alpy, SA, ... are complementary instruments. My purpose concern in general
the exceptionnal contain of stellar spectra in comparison of large
band photometry (I exclude for the moment precise rattachement
to standard photometriuc system, BRVI photometer are the
best instruments for this).

The backgroung attenuation can improve precision and with
some precaution, a slit spectrograph can give results in
amateur spectrophotometry. It is demonstrated with LISA spectrograph for example.
I have also some materials with Alpy (ensemble photometry, taking into
account the atmosphere transmission...). This will be the subject of a future post.

Below new spectra of active galaxies. NGC 3077 is a compagnon of M81/ M82 group.

Image

Note ALPY slit image for Messier M82 (reduced by a factor 0.6):

Image

NGC 4051 Seyfert galaxy:

Image

Another Seyfert galaxy (NGC 5548):

Image

All these spectra are the very first taken with ALPY 600 (we are in a
commissioning phase !) .

Christian
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Re: Alpy 600 spectrograph - Some results

Postby Christian Buil » Fri Feb 22, 2013 3:19 pm

Some configuration of Alpy 600 system:

Quelques vues du système Alpy 600 :

D'abord le coeur du module de base (avec ici une fente réfléchissante
pour être utilisée avec le module de guidage) :

Image

Le configutation la plus simple, avec montage direct sur
le télescope via un coulant :

Image

Pour faciliter le pointage, on peut bien sur utitikser un système
filp-mirror courant :

Image

Le module de base couplée au module de guidage
(la caméra science est ici une Atik460EX et la caméra de guidage
est une Atik314L+, mais bien sur tout autre configuration est possible) :

Image

Le système Alpy600 prèt à être utilisé sur un télescope SC pour
la spectrographie d'objets faibles (noter le réducteur de focale
pour exploiter Alpy 600 avec une ouverture de l'ordre de f/6.5 - on
peut même pousser la luminosité jusqu'à f/5, voir f/4 - c'est calculé
pour) :

Image

Christian
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Re: Alpy 600 spectrograph - Some results

Postby Francois Teyssier » Fri Feb 22, 2013 6:45 pm

C'est superbe.
Exactement ce dont je rêvais en quittant le stage OHP en 2009 ...

Pourrais-tu nous montrer des spectres obtenus sans la fente ?
Par rapport au LISA est-ce que tu arrives à obtenir des objets encore plus faibles?

François

PS : bravo à toi et à Shelyak
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Re: Alpy 600 spectrograph - Some results

Postby Christian Buil » Sun Feb 24, 2013 11:56 pm

A compararison of ALPY 600 spectrograph (R=600) and LISA spectrograph (R=950) performances
on the same object, nova Monocerotis 2012, with the same telescope, the same CCD camera
and the same exposure:

La performance comparée des spectrographe ALPY 600 r=600) et LISA (R=950) sur le
même objet, la nova Monocerotis 2012, observé avec le même télesccope, la
même caméra CCD et le même temps de pose :


Image

Here a zoom on faint features:

Un zoom sur les faibles détails :

Image

The UV part of the spectrum:

La partie ultraviolette du spectre :

Image

and now Halpha :

Image

Higher apparent resolution of LISA spectrograph seem modest here because the
spectral lines are broad and well resolved (it is a nova!). The signal to noise ratio is
very similar for both cases. The nova is at V=12 during the observation.

La résolution apparente supérieure du spectrographe LISA est ici modeste
car les raies spectrales sont larges et bien résolues (rappelez-vous que l'on observe
ici une nova).


Christian
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Re: Alpy 600 spectrograph - Some results

Postby Francois Teyssier » Mon Feb 25, 2013 6:29 am

C'est très bon.
La résolution paraît plus constante que pour le Lisa. Et du coup un résultat qui semble même meilleur dans le bleu/UV
Cela étant, comme tu le fais remarquer, les raies de Nova Mon 2012 sont naturellement très larges.
Le véritable test consistera à comparer les spectres d'une nébuleuse planétaire et de voir comment H gamma et [OIII] 4363 d'une part, [SII] 6716 et 6730 d'autre part sont séparés.
IC 418 est bien placée en ce moment (toutefois [OIII] 4363 trés faible)

François
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Re: Alpy 600 spectrograph - Some results

Postby Robin Leadbeater » Mon Feb 25, 2013 12:38 pm

Hello Christian,

I am interested in the relative efficiency of the two instruments. Are these spectra individually scaled to the continuum or do they show the true relative flux for the two instruments?

Thanks
Robin
LHIRES III #29 ALPY 600 Star Analyser 100/200 ATIK314L+ C11 EQ6
http://www.threehillsobservatory.co.uk
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Re: Alpy 600 spectrograph - Some results

Postby Christian Buil » Mon Feb 25, 2013 8:21 pm

Robin,

Each spectra are scaled to unity intensity near 6750 A. The absolute efficiency is not easy to evaluate and to compare (resolution is not the same, also dispersion).

Noise is equivalent between the two spectra, but remember that the spectral resolution is lower for Alpy. ALPY efficiency is probably a little less than LISA, but still very honest.
It takes a little time for most accurate results.

Here a more representative resolution test concerning planetary emission lines (23 microns slit). Note the [S II] doublet easy to separate with LISA, and at the limit with ALPY 600.
Clearly, LISA display a better resolution performance ;)

Image

Image

Remember also that LISA spectrograph act as a focal reducer (X 0.62), which makes it more efficient on faint extended objects or more efficient on large telescopes.

ALPLY is not a competitor of LISA. The interest of ALPY 600 is elsewhere.

Christian
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Re: Alpy 600 spectrograph - Some results

Postby Christian Buil » Mon Mar 04, 2013 10:28 pm

Le système Alpy 600 complété par le module d'étalonnage (la boite blanche), avec trois fonctions :

1- lampe spectrale Ne/Ar
2 - lampe blanche pour les flat
3 - obturation du faisceau

The Aply 600 completed by a calibration optionnal module (the white box), with three functions:

1 - Ne/Ar spectral lamp
2 - tungsten lamp for flat-field
3 - shutter


Image

Un exemple type d'utilisation, surveillance d'étoiles variables faible (suite à une alerte AAVSO) :

A typical application example concerning an AAVSO alert on a faint target, BT Mon old nova possible outburst:

Image

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