spectro-aras.com

To all :

Need help

The solution given by Richard Walker, to calibrate spectrographs with RELCO SC480, made me decide to build me an echelle.

Taking different optical elements that I already had, the composition of the echelle is:


A focal reducctor Alan Gee Mark II, to let the focal F 7 ( telescope F 10, SC16 MEADE).

Slit: a of Shelyak Instruments, 50 microns, bounded longitudinally, with more or less success, with black tape. I know that I lose with 50 micron resolution, but I can see fainter objects.

Collimator: an objective of finder of 30 mm. in diameter and 125 mm. focal.

Echelle grating: I bought in the Optometrics, USA, of 50x25 mm, 63º and 79 l / mm.

Disperser: A transmission grating of 2 " of diameter and 208 l / mm. Baader-Planetarium, discontinued today.

The Objective: An old ASAHI PENTAX 1.8 to focal 85 mm.

CCD: An old AUDINE with KAF1603 ME (the AUDINE have trouble sealing and chip freezes). Possibly going to change a ATIK314L +.


I made a "lines.lst" with wavelengths detailed in R.Walker.

With ISIS, I tried reducing images of "daylight" and RELCO "but it does not work the file" check2.fit "I do not know what I do wrong. I guess it is because ISIS is configured to Schelle.

What solution have to calibrate the spectra of the echelle ? Is possible with the ISIS ?

Who asks me, I can send FITS of the "daylight" and RELCO and others.

Thank you, for your attention, J.Guarro.

I think ISIS expects a prism cross disperser and so is looking for curved spectra. This might be the issue.

Regards Andrew

Hi Joan,

I have built an echelle similar to yours with a grating cross disperser. ISIS is quite useful for analyzing these echelle spectra. Important is the adjustment of the angles alpha, beta, gamma for successful calibration. In addition the rotation of the camera is a critical parameter. If you tell a little more how far you got with analyzing your spectra I probably can help you more. You can also send me a private message or email if you have more questions or want to send me some data. A calibration spectrum, a sky spectrum and a flat (2D) would be helpful as well as the configuration file.

Best regards,

Martin

Hello Andrew:

Agree with what you say. I also came to this conclusion.

But sacrificing the reliability and agility of the ISIS is a step backwards.

We hope to find a solution ...

Regards, Joan.

Hallo Martin:

Thank you for your offer to help me, I hope not to get in too big a mess.
For private mail, send you me the files requested.

Thanks for all, Joan.

To all :
In recent weeks, I have conducted tests with the echelle, the results have been unstable.
I thank Martin Dubs for him generous and patient support, in the collimation and treatment echelle spectra.
ISIS has proven to be a good software, is surprisingly agile and reliable.
The AudeLA, use it to follow, well.

Attached here, graphic three stars of different Declination, have drawn his instrumental response. As you can see, the instrumental response of no use for the other two.
I think, the basis of the problem is that I can not get a good picture of tungsten, which has to be unique for each star.
I think the solution would be to install an optical fiber and a tracking box, leaving the echelle unmoving.

Have questions.
Fiber optics, micro lenses should carry at their ends?
What pinhole with reflective surface, use in tracking box?

I ask all sorts of suggestions.
Regards, Joan Guarro.

Hi Joan,

I think you're right : the spectro should be independent of the telescope and placed in a local near the telescope (less than 20m) .

Once set, the spectro don't have shift (except temperature variations).

With my 2 echelle spectrograph, I take Tungstène and LED (to identify order) just one time at the beginning of the night and I take calibration lamp (Th/ar) after each target.

For fiber and its injection module you have 2 options:

- Buy the injection module from Shelyak :
http://www.shelyak.com/produit.php?id_p ... rubrique=7
It works very well

- Make it by yourself , but it is very difficult to achieve . The current project open source " Sardine " is working on this subject :
http://open-astronomy.org/sardine/?q=node/1
Sorry the website in only in French
Maybe you can contact them.

For fiber , there is no microlens , just a FC connector well aligned with the fiber and well polished.

Bonjour Olivier:

Merci pour ton réponse rapide.

Mon intention est de construire une boîte de suivi qui a le Relco et Tunsgteno et de travailler avec une seule fibre optique, qui va au spectrographe.

J'ai deux problèmes à résoudre. La première est la fibre optique et ses connexions.
Le second est le trou de 100 microns avec la surface réfléchissante. Dans ce cas, il y a deux options, l'une d'un trou sur verre de I mm. d'épaisseur, ( https://www.appliedimage.com/products/o ... ertures-oa ), L'autre un troud air sur une surface métallique de réflexion douteuse et de mauvaise qualité.

Je ne comprends pas très bien comment se comporte le cône de lumière sortant de la fibre optique (sans micro-lentille) pour être efficace dans le collimateur de l'echelle, un 30 mm. diamètre et focale 125 mm.

Il y a des jours, j'ai demandé pour l'inscription dans le forum de "La Sardine" Je ne l'ai pas encore reçu le pasword.

En 1 heure, avec ma femme, nous allons à Majorque, nous sommes à quelques jours, sans aucun mobile, pas d'ordinateur, pas de télescope ... Je vais répondre à des e-mails autour.

Bien cordialement, Joan.

To all :

After installing an optical fiber 2 meters long, it seems that the Echelle work, the calibration is accurate.

I baptized Echelle,with the catalan word "Mussol" is translated, Owl, Hibou, Eule, Gufo, Búho.

I thank everyone who helped me, especially Martin Dubs essential for their cooperation and patience when they note the setting and data reduction.

I hope you like it. Sincerely, Joan.

Hi Joan, all is processed with ISIS ? If ok, it is a very good new.

Your spectra seem very excellent, félicitation !!!!

Can you give more precision about the spectrographe (you use the 85 mm objective lens, that about the collimator, the fiber size, the final adopted for the fiber interface on the telescope...).

Christian