PF0011 – eShel II Spectroscope

A fiber spectroscope

It is based on our strong experience in spectroscopy (with design and manufacturing of the Lhires III and Lhires Lite) and nights of observations including with MuSiCoS & Narval spectroscopes. This practical experience helped us to design a robust and productive solution in the field.

We designed the spectroscope with Christian Buil, a higly recognized optician expert. The software module has been written by Michel Pujol, an expert in Tcl/Tk and AudeLA platform. They both complement our expertise to bring you the best solution in echelle spectroscopy for astronomy !

Choice of optical fibre has been made to increase radial velocities measurement accuracy and for a better confort in using the eShel.

The Echelle spectroscopy

This technique makes it possible to reach high spectral resolutions because it uses the diffraction orders > 20 of a grating. The spectrum obtained passes through a cross disperser that “cuts” the spectrum in several successive orders by occupying the entire surface of the sensor of the camera. This gives the entire spectral in visible range  on about twenty order (in the case of eShel).

Schematic diagram of an Echelle spectrograph (© Christian Buil)

The Echelle spectroscope

The main module that generates the Echelle spectrum. It covers the spectral range from about 450 to 700 nm with a resolution > 10000 (with an ATIK 460 Ex camera in 2×2 binning not included). It has a fiber input on FC / PC connector to fix the 50 μm object fiber.

Delta Sco spectrum (Be star). Note the H-alpha line in emission (click on the image to enlarge)

Canon 40D, 9 x 300 s, 8′ SCT télescope (C.Buil)

The eShel software

Easy to use, it is based on the AudeLA software  ‘opensource’, written in Tcl/Tk, works under MS Windows (several languages ​​available), it allows during the acquisitions of spectra, to remotely control the various units (injection unit  and calibration unit).

Spectrum reduction can be started right after the acquisition by generating a multi-HDU fits file. An export of the individual orders or the combined spectrum (all orders merged) can also be realized.

Example of calibrated spectrum of Beta Persei, between H-beta and H-alpha (click on the image to enlarge)

The complet eShel solution consists of 4 main modules

1- The fiber injection and guiding unit

2- The calibration unit

3- The Echelle spectroscope

4- The eShel software

You have to add to the set up, an optical fiber object of 50 µm, an optical fiber calibration of 200 µm, an autoguiding camera and a main camera for spectra

Example of raw spectra

Beta Lyr – Shelyak [:-)] & P Cygni – 7 x 300 s  8′ SCT   (Click to enlarge)

WR 140 and Nova Del 2013 1x600s 14′ SCT and ATIK 460EX bin 2×2  (Click to enlarge)

Example of animation of a pulsating star

Here is also a good exemple of echelle spectroscopy with an animation of raw images of BW Vul, a pulsating star. 5min expoures, 60cm f/3.5 telescope at pic du Midi; QSI 516s camera.

Here is a spectrogram of BW Vul around Sodium doublet :

For a personal quote, send an email to : contact@shelyak.com