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/ISIS2/SFS/Ionogram/PT22S NASA Collection ISIS 2 Topside Sounder Ionograms ISIS-2 Topside Sounder Ionogram CDFs at NASA's CDAWeb https://doi.org/10.48322/v11k-e045 2026-02-12T23:08:33Z 2026-05-15T13:29:41Z ISIS 2 Collection metadata of ionograms created. JMW 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/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. 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 analysis, 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 microseconds 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 and and a swept-frequency portion. The time resolution between ionograms is typically 14 or 22 seconds depending on the frequency sweep range. Users please acknowledge the Coordinated Data Analysis Web (CDAWeb) at the NASA Goddard Space Flight Center, ISIS-2 SFS instrument Principal Investigator J. H. Whitteker and ISIS Data-Restoration project lead Robert F. Benson. Whitteker, James H. 2025-11-14T16:02:30Z 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 ISIS/Alouette Topside Sounder Data Restoration Project https://nssdc.gsfc.nasa.gov/space/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=1971-024A-01 Information about the Sweep Frequency Sounder experiment on ISIS-2. spase://VWO/NumericalData/ISIS2/SFS/ISIS2_Ionogram_CDF_PT22S spase://VWO/NumericalData/ISIS2/SFS/Ionogram.PT22S spase://VSPO/NumericalData/ISIS2/SFS/Ionogram/PT22S 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 HTTPS from SPDF https://spdf.gsfc.nasa.gov/pub/data/isis/topside_sounder/ionogram_cdf/isis2/ HTTPS access to repository of ISIS-2 Ionograms in CDF format at NASA CDAWeb 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 Please acknowledge the CDAWeb team at NASA/GSFC/SPDF ISIS-2 Topside Sounder Average Ionogram over Ahmedabad, India: AME, Latitude 23, Longitude 73 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Ahmedabad/PT22S 1973-02-03T04:00:26Z 1978-01-23T07:28:43Z Spherical GEO 23 73 ISIS-2 Topside Sounder Average Ionogram over Ascension Island, United Kingdom: ACN, Latitude -8, Longitude 346 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/AscensionIsland/PT22S 1975-01-09T01:22:59Z 1978-09-28T16:37:11Z Spherical GEO -8 346 ISIS-2 Topside Sounder Average Ionogram over Brazzavillle, Congo: BRZ, Latitude -4, Longitude 15 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Brazzaville/PT22S 1972-08-05T16:17:40Z 1975-09-25T16:12:59Z Spherical GEO -4 15 ISIS-2 Topside Sounder Average Ionogram over Fairbanks, AK: ULA, Latitude 65, Longitude 212 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Fairbanks/PT22S 1972-12-31T00:00:00Z 1979-07-30T02:17:45Z Spherical GEO 65 212 ISIS-2 Topside Sounder Average Ionogram over Falkland Island, United Kingdom: SOL, Latitude -52, Longitude 302 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/FalklandIslands/PT22S 1972-01-12T16:31:05Z 1972-12-10T00:57:02Z Spherical GEO -52 302 ISIS-2 Topside Sounder Average Ionogram over Johannesburg, South Africa: BUR, Latitude -26, Longitude 28 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Johannesburg/PT22S 1972-08-07T15:26:03Z 1976-01-16T19:18:39Z Spherical GEO -26 28 ISIS-2 Topside Sounder Average Ionogram over Kashima, Japan: KSH, Latitude 36, Longitude 141 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Kashima/PT22S 1972-01-01T00:01:10Z 1984-01-06T14:08:01Z Spherical GEO 36 141 ISIS-2 Topside Sounder Average Ionogram over Kerguelen Island, France: KER, Latitude -49, Longitude 70 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/KerguelenIsland/PT22S 1977-01-01T00:01:37Z 1984-01-27T18:16:53Z Spherical GEO -49 70 ISIS-2 Topside Sounder Average Ionogram over Kourou, French Guyana: KRU, Latitude 5, Longitude 307 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Kourou/PT22S 1973-02-06T01:16:08Z 1978-07-23T22:07:30Z Spherical GEO 5 307 ISIS-2 Topside Sounder Average Ionogram over Kwajalein, Marshall Islands: KWA, Latitude 9, Longitude 168 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Kwajalein/PT22S 1978-01-10T08:46:53Z 1978-11-09T07:38:18Z Spherical GEO 9 168 ISIS-2 Topside Sounder Average Ionogram over Las Palmas, Canary Island, Spain: CNA, Latitude 28, Longitude 345 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/LasPalmas/PT22S 1974-01-16T17:42:39Z 1976-02-01T11:15:40Z Spherical GEO 28 345 ISIS-2 Topside Sounder Average Ionogram over Lauder, New Zealand: LAU, Latitude -45, Longitude 170 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Lauder/PT22S 1973-01-01T04:14:29Z 1981-01-18T15:47:50Z Spherical GEO -45 170 ISIS-2 Topside Sounder Average Ionogram over Orroral, Australia: ORR, Latitude -36, Longitude 149 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Orroral/PT22S 1973-03-15T03:33:11Z 1981-07-20T20:42:22Z Spherical GEO -36 149 ISIS-2 Topside Sounder Average Ionogram over Ottawa, QC, Canada: OTT, Latitude 45, Longitude 284 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Ottawa/PT22S 1971-11-11T18:18:16Z 1984-01-04T05:16:00Z Spherical GEO 45 284 ISIS-2 Topside Sounder Average Ionogram over Ouagadougou, Burkina Faso: ODG, Latitude 14, Longitude 359 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Ouagadougou/PT22S 1972-08-06T05:36:37Z 1979-11-22T15:25:12Z Spherical GEO 14 359 ISIS-2 Topside Sounder Average Ionogram over Quito, Equador: QUI, Latitude -1, Longitude 281 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Quito/PT22S 1973-01-03T02:22:10Z 1979-10-18T04:22:30Z Spherical GEO -1 281 ISIS-2 Topside Sounder Average Ionogram over Resolute Bay, NU, Canada: RES, Latitude 75, Longitude 265 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/ResoluteBay/PT22S 1971-04-01T09:22:52Z 1983-01-13T11:06:43Z Spherical GEO 75 265 ISIS-2 Topside Sounder Average Ionogram over Santiago, Chile: SNT, Latitude -33, Longitude 298 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Santiago/PT22S 1973-06-15T09:48:17Z 1980-03-21T09:09:03Z Spherical GEO -33 298 ISIS-2 Topside Sounder Average Ionogram over Sodankyla, Finland: SOD, Latitude 67, Longitude 27 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Sodankyla/PT22S 1977-12-11T21:47:50Z 1978-09-13T21:01:48Z Spherical GEO 67 27 ISIS-2 Topside Sounder Average Ionogram over Syowa Base, Antartica: SYO, Latitude -69, Longitude 40 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/SyowaBase/PT22S 1973-02-03T05:49:37Z 1983-01-13T11:06:43Z Spherical GEO -69 40 ISIS-2 Topside Sounder Average Ionogram over Terre Adelie, Antarctica: ADL, Latitude -67, Longitude 140 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/TerreAdelie/PT22S 1973-01-12T10:18:21Z 1983-02-03T18:47:56Z Spherical GEO -67 140 ISIS-2 Topside Sounder Average Ionogram over Tromso, Norway: TRO, Latitude 70, Longitude 19 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Tromso/PT22S 1973-01-19T10:38:36Z 1977-10-06T20:20:00Z Spherical GEO 70 19 ISIS-2 Topside Sounder Average Ionogram over Winkfield, United Kingdom: WNK, Latitude 51, Longitude 359 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. spase://NASA/NumericalData/ISIS2/SFS/AverageIonogram/Winkfield/PT22S 1973-03-14T11:55:35Z 1979-07-15T04:35:11Z Spherical GEO 51 359