{"@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": "These Ionograms were digitized from the original ISIS-2 7-Track Analog Telemetry Tapes using the Facilities of the former Data Evaluation Laboratory at the NASA/GSFC. This Data Restoration Project is headed by Dr. R.F. Benson (NASA/GSFC). Ionograms were digitized at the Rate of 40,000 16-bit samples/s. This Sample Rate is higher than the Nyquist Frequency of 30 kHz. The Sample Frequency of 40 kHz provides a Measurement every 25 µs corresponding to an Apparent Range Interval equal to 3.75 km from c*t/2, where c is the Speed of Light. Ionograms with this Sample Rate are designated as 'Full' Ionograms because they have the full 3.75 km Apparent-Range Resolution. The Ionograms used for most Analyses, and those available from CDAWeb, were produced by averaging every four Samples of the Sounder-Receiver Video Amplitude Output to yield an average Value every 100 µs corresponding to an Apparent-Range Resolution of 15 km. These Ionogram Files are referred to as 'Average' Files with Standard Resolution. Each Ionogram consists of a Fixed-Frequency Portion and a Swept-Frequency Portion. The Time Resolution between Ionograms is typically 14 or 22 s depending on the Frequency Sweep Range.", "distribution": [{"@type": "dcat:Distribution", "downloadURL": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-009A", "format": "BIN", "mediaType": "application/octet-stream"}, {"@type": "dcat:Distribution", "downloadURL": "https://spdf.gsfc.nasa.gov/isis/isis-status.html", "format": "HTML", "mediaType": "text/html"}], "identifier": "/SDE/SPASE_JSON/|0bdb625ebfbf58dcc4638b7abb6205b1", "keyword": ["auroral-kilometric-radiation-akr", "ducted-echoes", "field-aligned-irregularities-fai", "ground-echoes", "ground-reflections", "ionospheric-echoes", "ionospheric-reflections", "plasma-resonance", "plasma-waves", "solar-type-iii-bursts", "spectrum", "swept-frequency-sounder", "topside-ionosphere", "topside-sounder", "upper-hybrid-noise-band", "wave-scattering", "waves-active-ionogram"], "license": "https://www.usa.gov/government-works", "modified": "2026-04-06", "programCode": ["026:000"], "publisher": {"@type": "org:Organization", "name": "NASA Space Physics Data Facility (SPDF) Data Services"}, "theme": ["Heliophysics"], "title": "ISIS-2 Topside Sounder Average Ionogram over Quito, Equador: QUI, Latitude -1, Longitude 281"}