{"product_id":"shelyak-se0121","title":"Shelyak Grating module for the Lhires III - 1800 l\/mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e\n\u003cstrong\u003eGrating Ruling:\u003c\/strong\u003e 1800 lines\/mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatibility:\u003c\/strong\u003e Shelyak Lhires III Spectroscope\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFunction:\u003c\/strong\u003e Alternative module to change native resolution\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUse Case:\u003c\/strong\u003e Wider spectral coverage at lower resolution\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section-center\"\u003e\n      \u003ch2\u003eGrating module for the Lhires III - 1800 l\/mm\u003c\/h2\u003e\n      \u003cp\u003eThis interchangeable grating module provides a ruling of 1800 lines\/mm, specifically designed to alter the native high-resolution capabilities of the Shelyak Lhires III spectroscope. It allows you to trade the maximum resolving power of the standard 2400 l\/mm grating for a significantly wider spectral window in a single exposure.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eThe 1800 l\/mm Grating: Trading Resolution for Spectral Range\u003c\/h3\u003e\n      \u003cp\u003eIn spectroscopy, there is a fundamental trade-off between resolution and spectral coverage. This 1800 l\/mm grating module for the Lhires III is engineered for situations where capturing a broader range of wavelengths is more critical than achieving the highest possible resolution. By decreasing the line density from the standard 2400 l\/mm, this grating disperses light less, fitting more of the spectrum onto your camera sensor.\u003c\/p\u003e\n      \u003cp\u003eThis makes the 1800 l\/mm grating ideal for analyzing objects with broad emission or absorption features, such as supernovae (SNe), comets, or cataclysmic variable stars. It's the right choice when the scientific goal is classification or monitoring changes across a wide spectral range, rather than measuring the precise radial velocity of a single spectral line.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eLhires III 1800 l\/mm vs. Standard 2400 l\/mm Grating\u003c\/h3\u003e\n      \u003cp\u003eThe Lhires III spectroscope ships with a 2400 l\/mm grating, which is optimized for high-resolution studies of specific, narrow spectral regions. This alternate 1800 l\/mm module extends the instrument's capabilities, turning it into a more adaptable research tool.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eStandard 2400 l\/mm Grating:\u003c\/strong\u003e Use this for maximum resolving power. It excels at splitting close binary star lines, measuring the Doppler shift in stellar spectra, or studying the fine structure of nebular emission lines like H-alpha and OIII.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eOptional 1800 l\/mm Grating:\u003c\/strong\u003e Choose this module for survey work or for targets where context is key. It allows you to capture, for example, the H-alpha, H-beta, and H-gamma lines of a Be star in a single frame, something not possible with the higher-resolution grating.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhy would I choose the 1800 l\/mm grating for my Lhires III instead of the standard 2400 l\/mm?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYou would choose the \u003cstrong\u003e1800 l\/mm grating\u003c\/strong\u003e when your primary goal is to capture a wider range of wavelengths in a single exposure. The standard \u003cstrong\u003e2400 l\/mm grating\u003c\/strong\u003e offers higher resolution but sees a smaller piece of the spectrum. The 1800 l\/mm module is for applications like classifying supernovae or studying comets, where broad spectral features are more important than resolving fine details.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat astronomical targets are best for the Lhires III with the 1800 l\/mm grating?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe 1800 l\/mm grating is ideal for targets with broad or multiple, widely-spaced spectral features. Good examples include:\u003c\/p\u003e\n    \u003cul\u003e\n      \u003cli\u003e\n\u003cstrong\u003eSupernovae (SNe):\u003c\/strong\u003e For classification based on broad silicon or hydrogen absorption lines.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cstrong\u003eComets:\u003c\/strong\u003e To capture multiple molecular emission bands (like C2) simultaneously.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cstrong\u003eBe Stars:\u003c\/strong\u003e To observe the profile of hydrogen Balmer lines (H-alpha, H-beta, etc.) in one frame.\u003c\/li\u003e\n      \u003cli\u003e\n\u003cstrong\u003eVariable Stars:\u003c\/strong\u003e For general spectrophotometry across a wide passband.\u003c\/li\u003e\n    \u003c\/ul\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 1800 l\/mm grating a direct replacement for the Lhires III's original grating?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, this is a fully compatible, interchangeable module designed by Shelyak specifically for the Lhires III spectroscope. It is intended to be swapped with the standard 2400 l\/mm grating to change the instrument's optical characteristics based on your observing target.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Lhires III 1800 l\/mm grating let me capture the spectrum of a star like Vega (Alpha Lyrae) in one shot?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe 1800 l\/mm grating provides a much wider field of view than the standard 2400 l\/mm grating, making it better suited for capturing broad stellar spectra. While the exact spectral range you can capture depends on your camera's sensor size and the specific wavelength you center on, this grating is the correct choice for projects that require observing multiple hydrogen Balmer lines in A-type stars like Vega in a single frame.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 1800 l\/mm grating affect the brightness of the spectrum from my Lhires III?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eBy dispersing starlight over a smaller area (lower dispersion), the 1800 l\/mm grating can produce a brighter continuum in the resulting spectrum compared to the 2400 l\/mm grating, assuming equal exposure time and conditions. This can be advantageous for obtaining a better signal-to-noise ratio on the overall spectrum of fainter objects.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eDoes installing the 1800 l\/mm grating on the Lhires III require recalibration?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, absolutely. Any time you change the diffraction grating in a spectroscope, you change the instrument's dispersion (how many angstroms per pixel). You will need to perform a new spectral calibration using a calibration lamp to accurately measure wavelengths with the 1800 l\/mm grating installed.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Shelyak_Lhires_III_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eShelyak Lhires III Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/shelyak-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eShelyak 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Shelyak","offers":[{"title":"Default Title","offer_id":52943046607133,"sku":"SHK-SE0121","price":1018.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Shelyak-Grating-module-for-the-Lhires-III-2400-l-mm-1_615c59cc-77ae-4187-b3f8-b440ca16be11.jpg?v=1789616301","url":"https:\/\/davidastro.com\/products\/shelyak-se0121","provider":"David Astro","version":"1.0","type":"link"}