{"@type": "dcat:Dataset", "accessLevel": "public", "bureauCode": ["026:00"], "contactPoint": {"@type": "vcard:Contact", "fn": "NASA Space Physics Data Facility", "hasEmail": "mailto:NASA-SPDF-Support@nasa.onmicrosoft.com"}, "description": "THEMIS Ground All Sky Imager Keograms for all observatories. Keograms are composed of thin images slices taken down the middle of all-sky images and graphed against time. Keograms allow for substorm analysis without the need for full sized raw images. The ASI stations each monitor a 170 degree field of view imaging the auroral oval at kilometer resolution. The ASI is comprised of a fisheye lens and CCD in a stainless steel enclosure topped with a transparent acrylic dome. Exposure control ranges from 5 s to 1 ms although the typical data rate is one image every 3 seconds. Silicone heaters keep the instrument within the nominal temperature range. During daylight hours a sun shades deploy to protect the CCD.", "identifier": "https://doi.org/10.48322/a2pk-b377", "keyword": ["imageintensity"], "landingPage": "https://doi.org/10.48322/a2pk-b377", "license": "https://www.usa.gov/government-works", "modified": "2026-06-15", "programCode": ["026:000"], "publisher": {"@type": "org:Organization", "name": "NASA Space Physics Data Facility (SPDF) Coordinated Data Analysis Web (CDAWeb) Data Services;THEMIS Data Repository at Berkeley"}, "theme": ["Heliophysics"], "title": "THEMIS Ground-based All Sky Imager Keogram, Level-1"}