The Lhires III spectroscope is the king of High Resolution (R = 18,000). Shelyak’s historic instrument was designed to observe details in one (or more) spectral lines. It’s the ideal tool for working with the Doppler effect and observing star activity.

An instrument of reference

The Lhires III spectroscope is Shelyak Instruments’ “historic” instrument. Designed from the CNRS Astrophysics School in 2003 for the observation of Be stars, it has since found a wide range of applications.

Resolution & spectral range

With a resolving power of R=18,000, it provides access to Doppler velocity measurements, as well as incredible detail in the profile of a line. The network module supplied as standard has 2400 lines/mm, giving full resolution. It can be replaced by an optional module, to access other resolutions – making the Lhires III a versatile instrument. You can adapt your resolution to your project. Weaker objects are then accessible: Novae, bright comets…

The spectral range covered is limited (of the order of ten nanometers, due to the need for high resolution), but you can select any wavelength in the visible range (400-750nm), thanks to a micrometer.

Numerous educational projects based on the Doppler effect are now possible, such as the rotation of Jupiter or Saturn.

Aperture

The F/10 aperture makes it particularly well suited to Schmidt-Cassegrain telescopes. But it can also be mounted on other, more open instruments (by adding a Barlow lens).

Guiding system

Thanks to its mirror slit, the Lhires III enables the target star to be precisely positioned and held in the slit. A guiding camera (not supplied) enables the telescope’s movements to be controlled (autoguiding), ensuring optimum observation.

Interchangeable slit

The interchangeable slit supplied as standard (15-19-23-35µm) means that the instrument can be adapted to most observations, giving priority to resolution or brightness if required. Other slits are also available as options (wide slits, photometric slits), to further extend the possibilities.

Mechanical interfaces

The Lhires III is supplied with a standard interface for Schmidt-Cassegrain telescopes. If you wish to adapt it to a 2″ eyepiece holder, use the optional 2″ adapter.

The CCD adaptor supplied as standard is suitable for ATIK cameras. (13mm mechanical backfocus). We offer a wide choice of adapter rings in our accessories catalog.

The guiding camera is C-mount.

Going further with Lhires III

In addition to the astrophysical knowledge it can provide, the Lhires III is also a tool for collaboration between amateur and professional astronomers: studying Be-type stars, tracking variable stars, etc. Numerous scientific papers have been based on observations with a Lhires III.

The support of a large community

The Lhires III is widely used around the world, and you can find many examples of use and advice on the Spectro-L discussion list: https://groups.io/g/spectro-l or on the spectroscopy forum: ARAS.

Specifications

• Resolution power R ~18000 (with 23 µm slit)
• Dispersion of 0.012nm (9µm pixels, around Hα)
• Aperture F/10
• Littrow architecture (the same achromatic doublet serves as collimator and lens)
• Adaptor rings for different types of detectors: CCD cameras, Digital Cameras, etc.
• Mirror slit for precise guiding (4 positions 15/19/23/35 µm).
• Slit length 8 mm
• Wavelength selected per micrometre throughout the visible range (400-700 nm)
• Included wavelength calibration lamp (argon/neon)
• Included tungsten lamp for flats
• Motorised calibration lamps for remote use
• Schmidt-Cassegrain adaptor (2″) as standard, mechanical backfocus 68.5 mm,
• Dual-lens C-mount guide port (focal ratio: 0.8x), mechanical backfocus 17.5 mm guide camera
• T-mount acquisition port, mechanical backfocus 55 mm (APN compatible)
• Interchangeable grating module (2400 tt/mm as standard)
• Light: 1.7 kg
• Compact: 250 mm x 200 mm x 83 mm
• Supplied in a hard case, with an eyepiece holder and a set of tools.

Composition

• The Lhires III spectroscope
• The interchangeable slit (15-19-23-35µm)
• Schmidt-Cassegrain telescope interface
• CCD adapter (for camera with 13mm back focus)
• Eyepiece holder (for observing the Sun’s spectrum by eye; eyepiece not supplied)

Documents

• The User Guide contains:
  → Setting the Lhires III
  → Your first steps in spectroscopy
  → Reminders of theory
  → Some projects
  Note: this document corresponds to the first version of Lhires III. Some parts are obsolete.
• A video tutorial on how to set up your LHIRES III
• A few Questions & Answers about Lhires III
• Lhires III+ update manual (argon-neon calibration module and motorised flat, guide mirror modification, new 0.8x guide port)
  Note: this update is now integrated in all Lhires III
• Argon-Neon spectrum with commentary (Manfred Schwarz): http://www.astrophoto.at/spectrum/Reference/ArNe.htm
• ISIS tutorial (for data reduction): http://www.astrosurf.com/buil/isis/guide_lhires/tuto1.htm
• Assembly instructions: for the AUDE project, the Lhires III was supplied as a DIY kit. The assembly instructions can help you understand the inner workings of the spectroscope.
• Set of drawings to help you integrate the Lhries III with your equipment.
• A STEP file giving the external volume of the Lhires III for integration in your telescope project, for example.
• Solar spectrum with comments, made by Olivier Garde with his Lhires III.
• Low-resolution solar spectrum
• You can also find more technical and practical information on the following websites:
  → http://www.astrosurf.org/buil/lhires3/project.htm
• Tuning your LHIRES III : online workshop

Applications

• High-resolution spectrum of variable stars
• Time series of the pulsating star (RR Lyr)
• High-resolution solar spectrum
• Radial velocities of stars Vr
• Star rotation: v.sin(i)
• Spectroscopic binaries
• Rotation of planets (Jupiter, Saturn)
• and so on…

Articles related to the Lhires III spectroscope:

Additional modules: technical specifications

Description	Shelyak ref.	Acc. type	Included	Comment
Integrated guiding module		Guiding module
Integrated calibration module		Calibration module
SPOX with 0.8m cable	ES0013	Other add-on modules		For remote control of flat and calibration lamps. Short cable for telescope installation.
SPOX with 5m cable	ES0012	Other add-on modules		For remote control of flat and calibration lamps. Câble long pour une utilisation à côté du télescope.