REFOS: Solar Soft X-ray Spectrophotometer on board Nanosatellite

REFOS: Solar Soft X-ray Spectrophotometer on board Nanosatellite | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article REFOS: Solar Soft X-ray Spectrophotometer on board Nanosatellite Anton Reva, Sergey Kuzin, Andrey Pertsov, Alexey Kirichenko, Sergey Dyatkov, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4938904/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Jul, 2025 Read the published version in Solar Physics → Version 1 posted 8 You are reading this latest preprint version Abstract In this work, we describe the design and flight performance of the REFOS instrument (from Russian REntgenovskiy FOto Spektrometr; in English "X-ray Photo Spectrometer"). REFOS is a soft X-ray spectrophotometer that registers full-disk integrated solar spectra (“Sun as a star”). It operates on board the Impulse-1 nanosatellite, which was launched on 24 June 2023. REFOS has a 1.2 – 30 keV spectral range, a 0.123 keV nominal full width at half-maximum (FWHM) resolution at 5.9 keV, and a cadence of 16 s. We illustrate the instrument flight performance using the spectra of the X5.0 flare that occurred on 31 December 2023 at 21:55 UT. For this flare, REFOS registered a meaningful signal in all of its energy bins. During the flare impulsive phase, the instrument clearly distinguishes non-thermal emission. During the flare peak, the spectrum exhibits signatures of the non-Maxwellian electron distribution. The observed continuum allows diagnosing the plasma temperature, and the observed spectral lines allow studying abundances of the Mg, Si, S, Ar, Ca, Fe, and Ni. Instrumentation and Data Management Spectrum X-Ray Flares Spectrum CubeSat Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 16 Jul, 2025 Read the published version in Solar Physics → Version 1 posted Editorial decision: Revision requested 07 Mar, 2025 Reviews received at journal 05 Mar, 2025 Reviewers agreed at journal 06 Feb, 2025 Reviewers agreed at journal 22 Aug, 2024 Reviewers invited by journal 20 Aug, 2024 Editor assigned by journal 20 Aug, 2024 Submission checks completed at journal 20 Aug, 2024 First submitted to journal 19 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4938904","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":352274413,"identity":"7516f85c-dd05-4235-8a2f-36d7dcfe7ae3","order_by":0,"name":"Anton 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