{"product_id":"shelyak-pf0011","title":"Shelyak eShel III Spectroscope","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eSpectral Range: 390nm to 750nm\u003c\/li\u003e\n\u003cli\u003eInstrument Type: Professional Echelle Spectroscope\u003c\/li\u003e\n\u003cli\u003eInput: Fiber-Optic Fed\u003c\/li\u003e\n\u003cli\u003eDesign: Modular Core Component\u003c\/li\u003e\n\u003cli\u003eApplication Focus: High-Resolution Astrophysical Analysis\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\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\u003eeShel III Spectroscope\u003c\/h2\u003e\n\u003cp\u003eThe Shelyak eShel III is a professional, fiber-fed echelle spectrograph designed for high-resolution analysis across a wide spectral range of 390nm to 750nm, enabling advanced research in topics such as exoplanetary science and stellar dynamics.\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\u003eProfessional Echelle Spectroscopy from 390nm to 750nm\u003c\/h3\u003e\n\u003cp\u003eThe eShel III achieves its high resolving power by employing an echelle grating, which uses high diffraction orders to spread light out in great detail. A cross-disperser prism then slices this spectrum into successive orders, stacking them to fill the entire surface of a camera sensor. This technique allows the instrument to capture the complete visible spectrum from 390nm to 750nm in a single exposure, without sacrificing resolution at any point in the range.\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\u003eFiber-Fed Design for High-Accuracy Radial Velocity\u003c\/h3\u003e\n\u003cp\u003ePrecision is paramount in spectroscopy, especially for radial velocity measurements used to detect exoplanets. The eShel III uses a fiber-optic feed to physically decouple the spectrograph from the telescope. This isolates the instrument from mechanical vibrations, flexure, and thermal fluctuations at the telescope, allowing it to be housed in a stable, temperature-controlled environment. This stability is the key to achieving the consistent, repeatable measurements required for professional research.\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 eShel III Core: Building a Complete Spectrographic System\u003c\/h3\u003e\n\u003cp\u003eThis product is the core eShel III spectroscope module and is not a standalone instrument. To create a fully operational system, it must be paired with a Fiber Injection and Guiding Unit (FIGU), a dedicated calibration module, and the required 50µm optical fibers for the target and calibration source. These components are available separately or as part of the complete eShel III system package. The entire system is controlled by the free Demetra software, which handles acquisition, remote control of the modules, and data reduction.\u003c\/p\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 an echelle spectroscope and why is the eShel III designed this way?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eAn \u003cstrong\u003eechelle spectroscope\u003c\/strong\u003e uses a special grating at a high angle to achieve very high spectral resolution. This creates overlapping spectral orders, which a second optical element (a cross-disperser) separates and stacks vertically on the sensor. This design allows the eShel III to capture a very wide spectral range (390nm to 750nm) at high resolution in a single image, something a traditional single-order spectrograph cannot do.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat additional components do I need to operate the eShel III Spectroscope?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe eShel III Spectroscope is the central module of a larger system. For operation, you will require:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eA \u003cstrong\u003eFiber Injection \u0026amp; Guiding Unit (FIGU)\u003c\/strong\u003e to inject the starlight into the fiber.\u003c\/li\u003e\n\u003cli\u003eA \u003cstrong\u003eCalibration Module\u003c\/strong\u003e for wavelength and flat-field calibration.\u003c\/li\u003e\n\u003cli\u003eTwo \u003cstrong\u003eoptical fibers\u003c\/strong\u003e (one for the star, one for calibration).\u003c\/li\u003e\n\u003cli\u003eA compatible astronomical camera, such as the ATIK 460Ex.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the fiber-fed design of the eShel III improve data quality for exoplanet hunting?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eDetecting the tiny Doppler shift in a star's light caused by an orbiting exoplanet requires extreme stability. By using an optical fiber, the \u003cstrong\u003eeShel III can be placed in a temperature-controlled room\u003c\/strong\u003e, completely isolated from the telescope's movement, vibrations, and changing orientation. This prevents instrumental shifts that could mimic or mask the real stellar signal, ensuring the measured radial velocity is highly accurate.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the eShel III for studying the spectral evolution of a variable star like BW Vulpeculae?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, absolutely. The eShel III is ideal for this type of research. Its ability to capture the entire visible spectrum at high resolution in a single exposure allows you to monitor changes in multiple spectral lines simultaneously over time. This is crucial for understanding the complex atmospheric pulsations and dynamics of stars like the Beta Cephei variable BW Vulpeculae.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat software is required to control the eShel III and its modules?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe entire eShel III system is controlled by Shelyak's \u003cstrong\u003eDemetra software\u003c\/strong\u003e, which is available as a free download. Demetra manages spectra acquisition, controls the FIGU and calibration modules remotely, and includes tools for data reduction, from raw images to calibrated spectra.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the eShel III Spectroscope a standalone instrument?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. This product is the \u003cstrong\u003ecore spectroscope module only\u003c\/strong\u003e. It is designed to be the heart of a complete spectrographic system and requires the additional components listed above for operation. Shelyak offers a complete package that includes all necessary modules for a functioning instrument.\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\u003eInstrument Type\u003c\/td\u003e\n\u003ctd\u003eFiber-Fed Echelle Spectroscope\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpectral Range\u003c\/td\u003e\n\u003ctd\u003e390nm to 750nm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInput Connector Type\u003c\/td\u003e\n\u003ctd\u003eFC\/PC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSystem Requirement\u003c\/td\u003e\n\u003ctd\u003eRequires FIGU, Calibration Module, and Optical Fibers (sold separately)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eControl Software\u003c\/td\u003e\n\u003ctd\u003eDemetra (Free Download)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\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_eShel_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 eShel Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/www.shelyak.com\/software\/?lang=en\" target=\"_blank\"\u003e\u003csvg xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewbox=\"0 0 640 512\" class=\"DAV-img-box\"\u003e\u003cpath fill=\"#0047a7\" d=\"M128 32C92.7 32 64 60.7 64 96l0 256 64 0 0-256 384 0 0 256 64 0 0-256c0-35.3-28.7-64-64-64L128 32zM19.2 384C8.6 384 0 392.6 0 403.2C0 445.6 34.4 480 76.8 480l486.4 0c42.4 0 76.8-34.4 76.8-76.8c0-10.6-8.6-19.2-19.2-19.2L19.2 384z\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDownload Software\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":52943035072797,"sku":"SHK-PF0011","price":11285.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Shelyak-eShel-III-Spectroscope-1_347805d2-ec23-482e-97ee-2fcea894c69b.jpg?v=1789616046","url":"https:\/\/davidastro.com\/fr-us\/products\/shelyak-pf0011","provider":"David Astro","version":"1.0","type":"link"}