Lhires III is a very high resolution spectrograph designed for amateur and educational astronomy. Numerous projects are within reach thanks to the technology involved in this instrument. Professional/amateur collaborations have been done with Lhires III spectrographs.
Shelyak Littrow High Resolution III Spectrograph
High resolution Shelyak Lhires III Spectrograph has featuresthat that will enable you to work on many projects that have not been accessible before. Designed for amateur and Educators, the Shelyak Lhires II Spectrograph has brought many professionals and amateurs together.
Since the Shelyak Littrow High Resolution III Spectrograph has been 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" f/10 telescopes, giving many beginners a way to carry out scientific experiments in their own backyard. Also, because this spectrograph is universal, all you need is a 2" 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. The mirror slit TAccurate centering with stable guiding during exposures makes your imaging experience a comfortable learning curve. While the mirror slit can be modified in width, it’s most important feature is the reflection of the field of view toward your guiding camera.
Lhires III Performance
The Shelyak Littrow High Resolution III Spectrograph features 2400 lines/ mm grating, for resolution power of approximately 17000. For lower-resolution projects, the grating can be effortlessly changed. These grating are available in 150, 300, 600, or 1200 lines/ mm. This can decrease the resolution to nearly 600. If you are using a DSLR camera you will find out, with a low resolution 300 lines/ mm grating, it can be shot in only one part.
The Lhires III spectrograph goes 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 SpcAudace allows amateurs to perform spectral analysis for visual purposes by aiding with the clarification of line profile details.
- power of resolution R ~18000
- resolution of 0.035nm near Halpha
- wavelength selected by micrometer
- mirror slit 15-35µm, reflective for guiding
- Schmidt-Cassegrain telescope adapter delivered in standard (two-inch available)
- NEW: internal argon-neon or neon lamp for calibration
- NEW: internal tungsten for flat
- NEW: motorised calibration for remote operations
- NEW: improved C-mount guiding port (focal ratio: 0.8x)
The guiding camera backfocus range is 15.5mm to 21mm with a C-thread (1inch diameter, 32 threads per inch).
- switchable grating modules (2400 gr/mm in standard; 1800 gr/mm, 1200 gr/mm, 600 gr/mm, 300 gr/mm and 150 gr/mm in option)
- possibility to put an eyepiece
- photo tripod adapter available for public outreach (visual solar spectrum)
See otherwise our detailed page on Lhires III
Look at the thesis done with a Lhires III by Benjamin G. Jenkins, Georgia State University:
A Study of the Lhires III Spectrograph on the Hard Labor Creek Observatory 20 inch Telescope
Lot of users are showing their results on Spectro-L Yahoo discussion group or ARAS forum so you may want to start from there:
Spectro-L : http://tech.groups.yahoo.com/group/spectro-l/
ARAS forum: http://www.spectro-aras.com/forum/
Of course, Christian Buil - original designer with us of the Lhires III - has an intensive web site full of informations and provide a free ISIS software to reduce your spectral data, see also ISIS tutorial:
There is an Exposure Time Calculator for Lhires III (ETCL) which should help you finding the best exposure time based on your equipment, location, target and of course grating used - this tool has been developped and correlated with actuall performance measurement with Lhires III spectrographs:
|Name||Shelyak Instruments - LHIRES III - High Resolution Spectrograph (Assembled and Tuned)|
|Custom Stock Status||Available - Ships in 3-5 Days|
The Lhires III is a versatile spectrograph. There are available gratings of differing resolutions that can be easily changed out. A micrometer is used to adjust the spectrograph to the desired wavelength range for a given project.
If there was one inconvenience with the LHires III, I would say that it is due to some minor flexure in the unit as it is moved from one target to another. This flexure, and/or possibly temperature changes, can cause a slight shift in the neon lines. For this reason, it is wise to take a neon calibration frame both before and after the series of images for a given target. But this takes only a matter of seconds to accomplish.
The LHires III very capable of producing high quality high resolution spectra that is acceptable for scientific research. I have given it a 4 star rating for value as it does appear to be a bit pricey. The 4 stars for quality are due to the flexure mentioned above.
(Posted on 2/7/2015)