Shelyak Lhires III Spectrograph

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Shelyak Lhires III Spectrograph

Shelyak Littrow High Resolution III Spectrograph

This very high resolution Shelyak Lhires III Spectrograph features technology that will enable users to work on many projects that have heretofore not been accessible. Designed for amateur and educational astronomy communites, the Shelyak Lhires II Spectrograph has facilitated many partnerships between professionals and novices.

When the Shelyak Littrow High Resolution III Spectrograph was first brought to market, it had become obvious that the resolution in available equipment was not high enough to allow for line profile changes to be seen. This spectrograph has been constructed to work best with 8-inch f/10 telescopes, giving many beginners a way to carry out scientific experiments in their own backyard. Furthermore, because this spectrograph is universal, all you need is a 2-inch or SCT adapter and it can be mounted on nearly all amateur telescopes. Shelyak produces a set of separately available adapters to permit most CCD cameras to be connected to the Lhires III. A common T-ring can be used to connect SLR cameras. Lastly, an eyepiece can also be connected to allow for the spectral lamp or solar spectra to be viewed.

Due to its easily portable size, the Shelyak Littrow High Resolution III Spectrograph can be operated with almost all mounts designed for amateurs. Align the spectrograph's slit with the RA axis to decrease signal loss from periodic errors. Accurate centering with stable guiding during exposures can be achieved thanks to the mirror slit. While the mirror slit can be modified in width, it's most crucial feature is that it reflects the field of view toward a guiding camera.

Lhires III Performance

The Shelyak Littrow High Resolution III Spectrograph features the standard 2400 lines/ mm grating, for resolution power of approximately 17000. For lower-resolution projects, the grating case can be effortlessly changed. These grating cases are available in 150, 300, 600, or 1200 lines/ mm. This can decrease the resolution to nearly 600. (See related products on the right for more information.) Users with DSLR cameras will find that in high resolution, approximately 20 parts are needed to shoot the entire visible spectral domain whereas with a low resolution 300 lines/ mm grating, it can be shot in only one part.

Spectra Processing



The Lhires III spectrograph takes its place between the camera and the telescope. Standard acquisition software is used to capture Spectra, but additional software may be necessary to center the target and consistently guide on it. Spectra extraction is a complicated procedure. IRIS software, which is available for free, comes with SpIRIS, a special module for spectra processing that permits spectra to be accumulated without manual interference for geometrical distortion. This module can then combine several exposures, draw out spectrum with a special algorithm, and meticulously assess spectra using atmospheric lines or integrated Neon lamp spectra. Finally, to correct for instrumental response, AudeLA/SpcAudace or Visual Spec software is needed.

Free software such as Visual Spec of SpcAudace allows amateurs to perform spectral analysis by aiding with the clarification of line profile details.

Shelyak Lhires III Spectrograph Features...


  • Power of resolution R ~ 17000
  • Resolution of 0.035 nm near H-alpha
  • Wavelength chosen by micrometer
  • Mirror slit 15 to 35 um, reflective for guiding
  • SCT adapter
  • Internal Neon lamp for calibration
  • Interchangeable grating modules (2400 gr/ mm in standard; 1200 gr/ mm, 600 gr/ mm, 300 gr/ mm and 150 gr/ mm optional)
  • Possible eyepiece attachment

Shelyak Instruments Product Number: ES0002



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