{"product_id":"shelyak-se0194","title":"Shelyak LISA \u0026 Lhires III Photometric Slit","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eEnables true spectrophotometry with LISA \u0026amp; Lhires III spectrographs\u003c\/li\u003e\n\u003cli\u003eDual-width design for simultaneous high-resolution spectra and total flux measurement\u003c\/li\u003e\n\u003cli\u003eCaptures all starlight for precise photometric data\u003c\/li\u003e\n\u003cli\u003eIdeal for studying variable stars, novae, and supernovae\u003c\/li\u003e\n\u003cli\u003eDirect-fit accessory for specified Shelyak instruments\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\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\u003eLISA \u0026amp; Lhires III Photometric Slit\u003c\/h2\u003e\n\u003cp\u003eThis Photometric Slit set for the Shelyak LISA and Lhires III spectrographs enables true scientific spectrophotometry by combining high-resolution spectral analysis with precise brightness measurement. Each slit features a unique dual-width design, with a narrow section to maintain the full resolving power of your instrument and a wide section to ensure every photon from your target star is collected. This allows you to create fully flux-calibrated spectra, essential for analyzing variable stars, novae, and other transient astronomical events.\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\u003eDual-Width Slit Design: The Key to Accurate Spectrophotometry\u003c\/h3\u003e\n\u003cp\u003eStandard spectroscopic slits are a compromise; narrow for high resolution, but at the risk of losing starlight due to atmospheric seeing, which corrupts brightness data. This photometric slit solves that problem by providing two slit widths in one. You can acquire a high-resolution spectrum using the narrow portion and a separate, photometrically accurate reading through the wide portion.\u003c\/p\u003e\n\u003cp\u003eBy combining observations from both sections, you can normalize the high-resolution spectrum to the total, accurate brightness of the star. This unlocks the ability to measure not just the composition and velocity of an object, but its absolute energy output across the spectrum—the core purpose of spectrophotometry.\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\u003eCompatibility and Use Case: For Shelyak LISA \u0026amp; Lhires III Spectrographs\u003c\/h3\u003e\n\u003cp\u003eThis set of slits is designed specifically as an accessory for the Shelyak LISA and Lhires III spectrographs. It replaces the standard slit, allowing observers to upgrade their instrument's capability from pure spectroscopy to quantitative spectrophotometry.\u003c\/p\u003e\n\u003cp\u003eThe primary application is for any research where both the spectral features and the absolute brightness of an object are changing. This is critical for characterizing the physics of cataclysmic variable stars, tracking the light curve and spectral evolution of a supernova, or monitoring the activity of young stellar objects.\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 the purpose of the LISA \u0026amp; Lhires III Photometric Slit?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe Photometric Slit allows you to perform \u003cstrong\u003espectrophotometry\u003c\/strong\u003e, which is the measurement of a star's spectrum (its light broken down by color) combined with an accurate measurement of its total brightness (photometry). This is crucial for creating scientifically accurate, flux-calibrated stellar spectra.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the dual-width design of the Photometric Slit work?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eEach slit has two sections:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eA \u003cstrong\u003enarrow part\u003c\/strong\u003e that provides the high spectral resolution needed to see fine details in a star's spectrum.\u003c\/li\u003e\n\u003cli\u003eA \u003cstrong\u003ewide part\u003c\/strong\u003e that ensures all the light from the star enters the spectrograph, even with poor seeing. This is essential for getting an accurate brightness measurement.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eBy taking observations with both parts of the slit, you can combine the detailed spectrum from the narrow part with the accurate brightness data from the wide part.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the Photometric Slit compatible with spectrographs other than the Shelyak LISA and Lhires III?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, this accessory is specifically designed for use with the Shelyak Instruments \u003cstrong\u003eLISA\u003c\/strong\u003e and \u003cstrong\u003eLhires III\u003c\/strong\u003e spectrographs. It is not intended for use with other models or brands.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy can't I just use a single wide slit for both spectroscopy and photometry?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile a wide slit captures all the star's light for good photometry, it dramatically reduces the spectrograph's resolution. Spectral lines would appear blurry and smeared, and fine details would be lost. The dual-width design allows you to get the best of both worlds: high resolution and accurate photometry, by taking separate, specialized exposures.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow would I use the Photometric Slit to study a variable star like Algol (Beta Persei)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eTo study an eclipsing binary like Algol (Beta Persei), you would take a series of exposures over time. For each observation, you would capture one spectrum with the narrow part of the slit to record any changes in the spectral lines (like doppler shifts), and another with the wide part to precisely measure the drop in brightness during the eclipse. This provides a complete picture of the system's dynamics.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIf I'm observing a supernova in a galaxy like the Whirlpool Galaxy (M51), what advantage does this slit give me?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eFor a supernova in M51, the Photometric Slit is invaluable. You would use the narrow slit to capture high-resolution spectra of the expanding debris, identifying elements and measuring their velocities. You would then use the wide slit to accurately measure the supernova's changing brightness, creating a light curve. Combining these allows you to calculate the total energy output and model the physics of the explosion far more accurately than with a standard slit.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\u003ca href=\"https:\/\/davidastro.com\/pages\/shelyak-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eShelyak 1-Year Warranty\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Shelyak","offers":[{"title":"Default Title","offer_id":52943051063581,"sku":"SHK-SE0194","price":305.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Shelyak-LISA-Lhires-III-Photometric-Slit-1_96e40eb5-63be-4000-a492-6d82fc431e67.jpg?v=1789616434","url":"https:\/\/davidastro.com\/fr\/products\/shelyak-se0194","provider":"David Astro","version":"1.0","type":"link"}