{"product_id":"shelyak-se0009","title":"Shelyak Grating module for the Lhires III - 150 l\/mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e150 lines\/mm Grating\u003c\/li\u003e\n\u003cli\u003eLow Resolution \/ Wide Spectral Range\u003c\/li\u003e\n\u003cli\u003eDesigned for the Shelyak Lhires III Spectroscope\u003c\/li\u003e\n\u003cli\u003eEnables Faint Object Spectroscopy\u003c\/li\u003e\n\u003cli\u003eUser-Interchangeable Module\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\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 - 150 l\/mm\u003c\/h2\u003e\n\u003cp\u003eThis 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.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eSurvey Mode for the Lhires III: The 150 l\/mm Advantage\u003c\/h3\u003e\n\u003cp\u003eThe 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 analyze faint, extended, or continuum-source objects that are inaccessible with the standard grating.\u003c\/p\u003e\n\u003cp\u003eThis makes the 150 l\/mm module the ideal tool for rapid classification of transient events like supernovae and novae, studying the broad emission features of comets, or capturing the full visible spectrum of faint deep-sky objects. It effectively adds a \"survey mode\" to your Lhires III, expanding its research capabilities significantly.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e150 l\/mm vs. 2400 l\/mm: Choosing the Right Grating for Your Target\u003c\/h3\u003e\n\u003cp\u003eSelecting the correct grating is critical for matching the instrument to your scientific goals. The two options serve fundamentally different purposes.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard 2400 l\/mm Grating:\u003c\/strong\u003e 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.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e150 l\/mm Grating Module:\u003c\/strong\u003e This is for low-resolution \"big picture\" spectroscopy. Use it to obtain a spectrum of a faint comet, classify a supernova by its broad spectral features, or monitor the spectral evolution of a variable star across the entire visible range at once.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the main application for the Shelyak 150 l\/mm grating module for the Lhires III?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary application is for low-resolution spectroscopy of faint or transient objects. It allows you to capture a wide spectral range in a single shot, which is essential for classifying objects like supernovae, analyzing the broad emission bands of comets, or studying faint nebulae.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the 150 l\/mm grating change the data I can collect with my Lhires III?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt 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 \u003cstrong\u003e150 l\/mm grating\u003c\/strong\u003e 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.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need to recalibrate my Lhires III when I switch to the 150 l\/mm grating?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, 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.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 150 l\/mm grating suitable for classifying a newly discovered supernova like SN 2023ixf with an 11\" SCT?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this is an ideal use case. An 11\" SCT provides enough light-gathering power, and the \u003cstrong\u003e150 l\/mm grating\u003c\/strong\u003e provides the wide spectral coverage needed to identify the characteristic broad absorption lines (like Silicon II for a Type Ia) used for supernova classification. The standard 2400 l\/mm grating would be unsuitable for this task as it would only show a tiny, unidentifiable fraction of the spectrum.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the 150 l\/mm grating to study the changing tail composition of Comet C\/2022 E3 (ZTF)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis is another excellent application. Cometary spectra are dominated by broad emission bands from molecules like C2 (the Swan bands) and CN. The \u003cstrong\u003e150 l\/mm grating\u003c\/strong\u003e allows you to capture all these features simultaneously to monitor how the comet's outgassing and composition evolve as it approaches and leaves the sun.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhen should I use the standard 2400 l\/mm grating instead of this 150 l\/mm module?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYou should use the standard \u003cstrong\u003e2400 l\/mm grating\u003c\/strong\u003e 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.\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\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":52943043690781,"sku":"SHK-SE0009","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_4dbbeda5-5e16-4f2e-800a-130d89ab377d.jpg?v=1789616227","url":"https:\/\/davidastro.com\/products\/shelyak-se0009","provider":"David Astro","version":"1.0","type":"link"}