2.7.1 https://spdx.org/licenses/ SPDX CC0-1.0 https://spdx.org/licenses/CC0-1.0.html Creative Commons Zero v1.0 Universal CC0 1.0 Universal is the Creative Commons license applicable to all publicly available SPASE metadata descriptions spase://NASA/Collection/Alouette2/SFS/PT31S NASA Collection Alouette-2 Topside Sounder Ionogram Data https://doi.org/10.48322/sksz-8704 2026-05-13T13:28:27Z 2026-05-13T21:14:17Z First releaseDate of the metadata These ionograms were digitized from the original Alouette 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/sec. This sample rate is higher than the Nyquist frequency of 30 kHz. The sample frequency of 40 kHz provides a measurement every 25 microseconds corresponding to an apparent range (c*t/2) interval of 3.75 km. The ionograms consist of swept-frequency operation (there is no fixed-frequency operation as in ISIS-1 and ISIS-2). The time resolution between ionograms is typically 31 seconds. Users please acknowledge the Coordinated Data Analysis Web (CDAWeb) at the NASA Goddard Space Flight Center, Alouette-2 SFS instrument Principal Investigator J. H. Whitteker and Alouette/ISIS Data-Restoration project lead Robert F. Benson. Whitteker, James H. 2025-11-14T16:01:55Z Space Physics Data Facility spase://SMWG/Person/James.H.Whitteker PrincipalInvestigator spase://SMWG/Person/Robert.F.Benson GeneralContact spase://SMWG/Person/Dieter.K.Bilitza GeneralContact spase://SMWG/Person/Dieter.K.Bilitza MetadataContact ISIS/Alouette Topside Sounder Data Restoration Project https://spdf.gsfc.nasa.gov/isis/isis-status.html ISIS/Alouette page maintained by NASA GSFC with science and instrument descriptions, data access, software, and publication lists en NSSDC's Master Catalog https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1965-098A-01 Information about the Sweep Frequency Sounder experiment on Alouette-2. spase://VWO/NumericalData/Alouette2/SFS/PT31S spase://VSPO/NumericalData/Alouette2/SFS/PT31S spase://SMWG/Repository/NASA/GSFC/SPDF Online Open https://spdx.org/licenses/ SPDX CC0-1.0 https://spdx.org/licenses/CC0-1.0.html Creative Commons Zero v1.0 Universal CC0 1.0 Universal is the Creative Commons license applicable to all publicly available NASA Heliophysics data products HTTP access to files at SPDF https://spdf.gsfc.nasa.gov/pub/data/alouette/topside_sounder/ionogram_cdaweb/alouette2/ FTP access to repository of Alouette-2 Ionograms in CDF format at NASA CDAWeb. The CDF files are organized by ground station, where each ground station is represented by a three letter ID and a two-digit code. The full names for each station are provided at https://spdf.gsfc.nasa.gov/isis/isis-table1-new.html en Subset, plot, list from CDAWeb https://cdaweb.gsfc.nasa.gov/sp_phys/ CDAWeb interactive interface for subsets, plots and lists of data CDF None Users please acknowledge the Coordinated Data Analysis Web (CDAWeb) at the NASA Goddard Space Flight Center, ISIS-1 SFS instrument Principal Investigator J. H. Whitteker and ISIS Data-Restoration project lead Robert F. Benson. Alouette-2 Topside Sounder Average Ionogram over Fairbanks, AK This Ionogram was digitized from the original Alouette 2 Analog Telemetry Data on 7-Track Tape using the Facilities of the Data Evaluation Laboratory at NASA GSFC spase://NASA/NumericalData/Alouette2/SFS/AverageIonogram/Fairbanks/PT31S 1965-11-29T06:20:12Z 1965-11-29T06:32:42Z Spherical GEO 65 212 Alouette-2 Topside Sounder Average Ionogram over Falkland Is., United Kingdom This Ionogram was digitized from the original Alouette 2 Analog Telemetry Data on 7-Track Tape using the Facilities of the Data Evaluation Laboratory at NASA GSFC spase://NASA/NumericalData/Alouette2/SFS/AverageIonogram/FalklandIslands/PT31S 1965-12-01T01:31:39Z 1966-12-28T03:00:28Z Spherical GEO -52 302 Alouette-2 Topside Sounder Average Ionogram over Lima, Peru This Ionogram was digitized from the original Alouette 2 Analog Telemetry Data on 7-Track Tape using the Facilities of the Data Evaluation Laboratory at NASA GSFC spase://NASA/NumericalData/Alouette2/SFS/AverageIonogram/Lima/PT31S 1966-11-11T20:34:08Z 1967-01-15T12:59:00Z Spherical GEO -12 283 Alouette-2 Topside Sounder Average Ionogram over Quito, Equador This Ionogram was digitized from the original Alouette 2 Analog Telemetry Data on 7-Track Tape using the Facilities of the Data Evaluation Laboratory at NASA GSFC spase://NASA/NumericalData/Alouette2/SFS/AverageIonogram/Quito/PT31S 1965-11-29T13:47:39Z 1968-01-01T04:12:17Z Spherical GEO -1 281 Alouette-2 Topside Sounder Average Ionogram over Santiago, Chile This Ionogram was digitized from the original Alouette 2 Analog Telemetry Data on 7-Track Tape using the Facilities of the Data Evaluation Laboratory at NASA GSFC spase://NASA/NumericalData/Alouette2/SFS/AverageIonogram/Santiago/PT31S 1965-11-29T13:42:37Z 1967-01-01T04:19:41Z Spherical GEO -33 298 Alouette-2 Topside Sounder Average Ionogram over Winkfield, United Kingdom This Ionogram was digitized from the original Alouette 2 Analog Telemetry Data on 7-Track Tape using the Facilities of the Data Evaluation Laboratory at NASA GSFC spase://NASA/NumericalData/Alouette2/SFS/AverageIonogram/Winkfield/PT31S 1966-03-30T05:48:19Z 1966-04-06T06:01:10Z Spherical GEO -33 298