{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,23]],"date-time":"2025-10-23T05:05:05Z","timestamp":1761195905860,"version":"build-2065373602"},"reference-count":20,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2013,8,6]],"date-time":"2013-08-06T00:00:00Z","timestamp":1375747200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with diffraction spectroscopy to improve knowledge of atmospheric constituents and their links to air-pollution\/climate. Direct beam hyper-spectral measurement of optical depth improves retrievals of gas constituents and determination of aerosol properties. Sky scanning enhances retrievals of aerosol type and size distribution. 4STAR measurements will tighten the closure between satellite and ground-based measurements. 4STAR incorporates a modular sun-tracking\/ sky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and future detector evolution. Technical challenges include compact optical collector design, radiometric dynamic range and stability, and broad spectral coverage. Test results establishing the performance of the instrument against the full range of operational requirements are presented, along with calibration, engineering flight test, and scientific field campaign data and results.<\/jats:p>","DOI":"10.3390\/rs5083872","type":"journal-article","created":{"date-parts":[[2013,8,6]],"date-time":"2013-08-06T12:33:17Z","timestamp":1375792397000},"page":"3872-3895","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":41,"title":["Spectrometer for Sky-Scanning Sun-Tracking Atmospheric Research (4STAR): Instrument Technology"],"prefix":"10.3390","volume":"5","author":[{"given":"Stephen","family":"Dunagan","sequence":"first","affiliation":[{"name":"Ames Research Center, NASA, MS 245-4, Moffett Field, CA 94035, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Roy","family":"Johnson","sequence":"additional","affiliation":[{"name":"Ames Research Center, NASA, MS 245-4, Moffett Field, CA 94035, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jhony","family":"Zavaleta","sequence":"additional","affiliation":[{"name":"Ames Research Center, NASA, MS 245-4, Moffett Field, CA 94035, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Philip","family":"Russell","sequence":"additional","affiliation":[{"name":"Ames Research Center, NASA, MS 245-4, Moffett Field, CA 94035, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Beat","family":"Schmid","sequence":"additional","affiliation":[{"name":"Pacific Northwest National Laboratory, Richland, WA 99325, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Connor","family":"Flynn","sequence":"additional","affiliation":[{"name":"Pacific Northwest National Laboratory, Richland, WA 99325, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jens","family":"Redemann","sequence":"additional","affiliation":[{"name":"Ames Research Center, NASA, MS 245-4, Moffett Field, CA 94035, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yohei","family":"Shinozuka","sequence":"additional","affiliation":[{"name":"The Ames Cooperative for Research in Earth Science and Technology (ARC-CREST), NASA, Moffett Field, CA 94035, USA"},{"name":"Bay Area Environmental Research Institute, Sonoma, CA 95476, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John","family":"Livingston","sequence":"additional","affiliation":[{"name":"SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michal","family":"Segal-Rosenhaimer","sequence":"additional","affiliation":[{"name":"Ames Research Center, NASA, MS 245-4, Moffett Field, CA 94035, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2013,8,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Schmid, B., Redemann, J., Russell, P.B., Hobbs, P.V., Hlavka, D.L., McGill, M.J., Holben, B.N., Welton, E.J., Campbell, J.R., and Torres, O. 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