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Shelyak Grating module for the Lhires III - 300 l/mm

Shelyak Grating module for the Lhires III - 300 l/mm

par Shelyak
UGC SHK-SE0008
CA$1,099.00 - CA$1,099.00
CA$1,099.00
CA$1,099.00 - CA$1,099.00
CA$1,099.00
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  • Grating for Lhires III Spectroscope
  • 300 lines/mm Ruling
  • Provides Lower Resolution and Wider Spectral Range
  • Complements the Standard 2400 l/mm Grating
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  • Description
  • FAQ
  • Specifications
  • In the Box
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  • Warranty

  • Grating module for the Lhires III - 300 l/mm

    The Shelyak Grating module for the Lhires III - 300 l/mm is an optional component designed to trade the high resolution of the standard 2400 l/mm grating for significantly broader spectral coverage in a single exposure. This 300 lines/mm grating fundamentally alters the instrument's capabilities, making it suitable for analyzing entire spectral classes of stars or fainter stars where wide spectral coverage is more critical than resolving fine absorption lines.

    From 2400 l/mm to 300 l/mm: Expanding Your Lhires III's Capabilities

    The Shelyak Lhires III spectroscope is supplied with a 2400 lines/mm grating, engineered specifically for high-resolution studies of specific spectral features. This 300 l/mm grating module offers the inverse capability, transforming your specialized instrument into a versatile survey tool.

    By reducing the line count, the 300 l/mm grating disperses light over a smaller angle, allowing a much wider range of wavelengths to fall onto your sensor at once. This trade-off is the core purpose of the module: sacrificing resolving power to gain spectral breadth.

    • Standard 2400 l/mm Grating: Delivers high resolution over a narrow spectral window. It is ideal for measuring the Doppler shift in a binary star's H-alpha line or studying fine line profiles of bright stars.
    • Optional 300 l/mm Grating: Provides lower resolution across a very wide spectral window. It is built for capturing the overall spectral energy distribution of an object, classifying a star's type, or monitoring a bright nova's evolution over about 110 nm of spectrum per image.

    Applications for Low-Resolution Spectroscopy with the 300 l/mm Grating

    With this module, your Lhires III becomes a tool for spectrophotometry and for fainter stars: the lower dispersion concentrates the light, increasing the signal-to-noise ratio per pixel. Shelyak's Lhires III table gives a limiting magnitude of 8.4 with this grating, against 5.0 with the 2400 l/mm (200 mm f/10 telescope, 1 h exposure, S/N 100).

    This grating is also essential for spectral classification. To determine if a star is a hot, blue O-type or a cool, red M-type, you need to see the overall shape of its blackbody curve and the presence of broad absorption features. The 300 l/mm grating covers about 110 nm per image (the whole visible range in about 4 images with Shelyak's reference KAF-0400 camera; more per frame with a larger sensor), making it a powerful tool for stellar astrophysics projects.

  • Why would I choose the 300 l/mm grating for my Lhires III when it comes with a 2400 l/mm grating?

    You would choose the 300 l/mm grating when your scientific goal requires a wide spectral range rather than high resolution. The standard 2400 l/mm grating is for detailed study of narrow spectral lines, while the 300 l/mm grating covers about 110 nm per image, useful for spectral classification or studying objects with broad emission features like novae.

    What is the main advantage of the 300 l/mm Lhires III grating module?

    The main advantage is spectral coverage. It allows your Lhires III to capture a much wider range of wavelengths in a single exposure compared to the standard high-resolution grating. This makes it possible to analyze the overall energy distribution of a star or record broad features over a wide window.

    Does the 300 l/mm grating reach fainter targets than the 2400 l/mm grating?

    Yes. Because the 300 l/mm grating has a lower dispersion, it concentrates the light more on your camera's sensor. Shelyak's Lhires III table gives a limiting magnitude of 8.4 with this grating against 5.0 with the 2400 l/mm (200 mm f/10 telescope, 1 h exposure, S/N 100), which suits fainter stars and bright novae.

    How does the 300 l/mm grating affect the spectrum I can capture with my Lhires III and an 8" SCT?

    With an 8" SCT, the 300 l/mm grating will allow your Lhires III to function as a powerful survey and classification instrument. You will be able to cover about 110 nm of the spectrum of moderately bright stars per image (about 4 images for the whole visible range with a KAF-0400 sensor), allowing you to classify them based on their overall spectral features (e.g., O, B, A, F, G, K, M types). This is a task that would be impossible with the narrow-band view of the standard 2400 l/mm grating.

    Can I use the 300 l/mm grating for spectral classification of stars like Vega (Alpha Lyrae)?

    Absolutely. The 300 l/mm grating is perfect for this application. For a star like Vega (Alpha Lyrae), an A0V-class star, this grating will allow you to easily capture the prominent, broad absorption lines of the Balmer series (Hydrogen-alpha, beta, gamma, etc.) that define its spectral type, in a few images (about 110 nm per image with Shelyak's reference KAF-0400 camera).

    Is swapping the grating in the Lhires III difficult?

    The grating module is designed for user installation, allowing you to switch between resolutions based on your observing targets for the night. While the process is straightforward, it requires care to avoid damaging the optical components. We strongly recommend consulting the official Lhires III user manual for detailed, step-by-step instructions before changing the grating.

  • Grating Ruling 300 lines/mm
    Compatibility Shelyak Lhires III Spectroscope
    Resolving power (R) About 1400 (H-alpha)

    • 300 l/mm Grating Module for Lhires III

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