{"product_id":"shelyak-se0006","title":"Shelyak Grating module for the Lhires III - 1200 l\/mm","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e1200 lines\/mm Grating\u003c\/li\u003e\n\u003cli\u003eDirect-Fit Module for Lhires III\u003c\/li\u003e\n\u003cli\u003eExpands Spectrograph Wavelength Coverage\u003c\/li\u003e\n\u003cli\u003eIdeal for Spectroscopic Surveys\u003c\/li\u003e\n\u003cli\u003eInterchangeable with Standard Grating\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\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\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 - 1200 l\/mm\u003c\/h2\u003e\n\u003cp\u003eSwap the standard 2400 l\/mm grating in your Shelyak Lhires III spectrograph for this 1200 lines\/mm module to trade high resolution for significantly broader spectral coverage in a single exposure. This module is an essential accessory for observers who need to characterize objects with unknown features or monitor phenomena across a wide spectral range, such as supernovae or comets.\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\u003eThe 1200 l\/mm Trade-Off: Broader Wavelength Coverage at Lower Resolution\u003c\/h3\u003e\n\u003cp\u003eIn spectroscopy, a grating's line density dictates the trade-off between spectral resolution and wavelength coverage. A higher line count, like the Lhires III's standard 2400 l\/mm grating, spreads the light out more, delivering higher resolution over a smaller spectral window. This 1200 l\/mm grating does the opposite; with fewer lines, it produces a less dispersed spectrum, allowing a much wider range of wavelengths to fall onto your sensor in a single frame.\u003c\/p\u003e\n\u003cp\u003eThis capability is critical for survey work, initial classification of variable stars, or capturing the full profile of objects with broad emission lines. Instead of taking multiple exposures to piece together a spectrum, you can capture the entire visible range at once, saving valuable observing time.\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\u003e1200 l\/mm vs. 2400 l\/mm: Choosing the Right Grating for Your Target\u003c\/h3\u003e\n\u003cp\u003eThe standard 2400 l\/mm grating is the correct tool for the high-resolution work the Lhires III is famous for—measuring precise radial velocities, studying detailed line profiles of Be stars, or resolving close binary systems spectroscopically. It prioritizes detail over breadth.\u003c\/p\u003e\n\u003cp\u003eThe 1200 l\/mm grating module excels when the scientific goal is characterization rather than fine measurement. It is the superior choice for:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSupernova and Nova Spectroscopy:\u003c\/strong\u003e Capturing the evolution of multiple, broad spectral features (like Silicon II or Hydrogen lines) simultaneously as the object brightens and fades.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eQuasar and AGN Characterization:\u003c\/strong\u003e Identifying highly redshifted emission lines across a wide spectral range to determine the object's distance and nature.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCometary Analysis:\u003c\/strong\u003e Observing molecular emission bands from species like C2 (Swan bands) which span a significant portion of the visible spectrum.\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\"\u003eWhy would I choose the 1200 l\/mm grating for my Lhires III over 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\u003e1200 l\/mm grating\u003c\/strong\u003e when your primary goal is to capture the widest possible range of wavelengths in a single exposure. The standard \u003cstrong\u003e2400 l\/mm grating\u003c\/strong\u003e provides higher resolution but covers a much narrower spectral window. The 1200 l\/mm module is for survey work and broad characterization, not fine detail analysis.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the main advantage of a lower-resolution grating like this 1200 l\/mm module for the Lhires III?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe main advantage is \u003cstrong\u003eefficiency\u003c\/strong\u003e. For objects like supernovae, comets, or quasars, important spectral features can be spread far apart. The 1200 l\/mm grating allows you to capture all of them in one shot, saving time and simplifying data acquisition compared to creating a mosaic of multiple high-resolution exposures.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 1200 l\/mm grating module difficult to install in the Lhires III?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, the Lhires III is designed for interchangeable grating modules. The process involves opening the access panel and carefully swapping the existing module with the new one. Always refer to your Lhires III manual for the specific procedure to avoid damaging the delicate grating surface.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIf I want to study the H-alpha line profile of Vega (Alpha Lyrae) with my Lhires III, is the 1200 l\/mm grating the right choice?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. For detailed analysis of a single, narrow spectral line like H-alpha, the standard \u003cstrong\u003e2400 l\/mm grating is the correct tool\u003c\/strong\u003e. Its higher resolution is necessary to reveal subtle shifts and profile changes. The 1200 l\/mm grating would show the line, but without the detail needed for scientific measurement of its profile.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI'm using my Lhires III on an 8\" SCT to monitor a supernova. Why is the 1200 l\/mm grating module a good tool for this?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eSupernovae exhibit broad, evolving spectral features across the entire visible spectrum. The \u003cstrong\u003e1200 l\/mm grating's\u003c\/strong\u003e wide spectral coverage is ideal for this task, as it allows you to capture the appearance and evolution of key features like the Silicon II (Si II) absorption line in Type Ia supernovae and the broad Hydrogen lines in Type II, all within a single frame.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes using the 1200 l\/mm grating module change the calibration process for the Lhires III?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, absolutely. You must perform a new spectral calibration after installing the 1200 l\/mm grating. The dispersion (angstroms per pixel) is different from the 2400 l\/mm grating, so your previous calibration files will no longer be accurate. You will need to create and save a new calibration profile for this specific setup.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eGrating Density\u003c\/td\u003e\n\u003ctd\u003e1200 lines\/mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eShelyak Lhires III Spectrograph\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApplication\u003c\/td\u003e\n\u003ctd\u003eLow Resolution, Wide Field Spectroscopy\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e1200 l\/mm Grating Module for Lhires III\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\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":52943042740509,"sku":"SHK-SE0006","price":738.0,"currency_code":"USD","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_b61d3287-6af2-4150-ae9e-8b534d66107a.jpg?v=1789616204","url":"https:\/\/davidastro.com\/en-us\/products\/shelyak-se0006","provider":"David Astro","version":"1.0","type":"link"}