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Shelyak Grating module for the Lhires III - 150 l/mm

Shelyak Grating module for the Lhires III - 150 l/mm

by Shelyak
SKU SHK-SE0009
$738.00 - $738.00
$738.00
$738.00 - $738.00
$738.00
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  • 150 lines/mm Grating
  • Low Resolution / Wide Spectral Range
  • Designed for the Shelyak Lhires III Spectroscope
  • Reaches Fainter Stars than the 2400 l/mm Grating
  • User-Interchangeable Module
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  • Description
  • FAQ
  • Specifications
  • In the Box
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  • Grating module for the Lhires III - 150 l/mm

    This 150 lines/mm grating module transforms the Shelyak Lhires III from a specialized high-resolution instrument into a versatile survey spectroscope. By replacing the standard 2400 l/mm grating, you dramatically lower the dispersion to capture a much wider spectral range in a single exposure, opening up new targets for scientific analysis.

    Survey Mode for the Lhires III: The 150 l/mm Advantage

    The core purpose of the Lhires III is high-resolution spectroscopy, but this requires bright targets and isolates a very narrow slice of the spectrum. The 150 l/mm grating module intentionally trades that high resolution for a massive increase in spectral bandwidth and throughput, allowing you to reach fainter stars (limiting magnitude 9.2 against 5.0 in Shelyak's Lhires III table: 200 mm f/10 telescope, 1 h exposure, S/N 100).

    This makes the 150 l/mm module well suited to following bright novae and bright stars, or covering the visible range in about 2 images (230 nm per image with Shelyak's reference KAF-0400 camera). It effectively adds a "survey mode" to your Lhires III, expanding its research capabilities significantly.

    150 l/mm vs. 2400 l/mm: Choosing the Right Grating for Your Target

    Selecting the correct grating is critical for matching the instrument to your scientific goals. The two options serve fundamentally different purposes.

    • Standard 2400 l/mm Grating: This is for high-resolution work on bright stars. Use it to detect the subtle Doppler shifts in binary star systems, analyze the fine absorption lines in a stellar atmosphere (like the Sodium D-lines), or measure precise radial velocities. Its spectral range is very narrow.
    • 150 l/mm Grating Module: This is for low-resolution "big picture" spectroscopy. Use it to follow a bright nova by its broad spectral features, or monitor the spectral evolution of a variable star over about 230 nm per image.

  • What is the main application for the Shelyak 150 l/mm grating module for the Lhires III?

    The primary application is low-resolution spectroscopy of fainter stars (limiting magnitude 9.2 in Shelyak's Lhires III table, against 5.0 for the 2400 l/mm grating). It covers about 230 nm per image (Shelyak's reference KAF-0400 camera), useful for classifying stars or following bright novae.

    How does the 150 l/mm grating change the data I can collect with my Lhires III?

    It fundamentally changes the trade-off between spectral resolution and wavelength coverage. Instead of a very detailed view of a tiny part of the spectrum (like with the standard 2400 l/mm grating), the 150 l/mm grating provides a lower-detail view of a much wider portion of the spectrum. This is better for understanding the overall nature of an object rather than its fine atmospheric details.

    Do I need to recalibrate my Lhires III when I switch to the 150 l/mm grating?

    Yes, absolutely. Any time you change the grating in a spectroscope, you must perform a new wavelength calibration. The dispersion, or how much the light is spread out per pixel, is completely different for the 150 l/mm grating compared to the standard 2400 l/mm grating. You will need to take new calibration frames with a reference lamp.

    When should I use the standard 2400 l/mm grating instead of this 150 l/mm module?

    You should use the standard 2400 l/mm grating when your scientific goal requires very high spectral resolution for bright targets. This includes measuring precise radial velocity shifts from stellar wobble, studying the detailed profiles of spectral lines in Be stars, or resolving close spectroscopic binaries.

  • Resolving power (R) R ~700 (H-alpha, Shelyak reference setup)
    Fits (mount / scope) Lhires III
    Fits Spectrograph Lhires III

    • Shelyak Grating module for the Lhires III - 150 l/mm

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  • Shelyak 1-Year Warranty