The International Ultraviolet Explorer (IUE) performed spectrophotometry at high (0.1-0.3 Å) and low (6-7 Å) resolution between 1150 Å and 3200 Å. The data cover a dynamic range of approximately 17 astronomical magnitudes: -2 to 10 for high dispersion; -2 and 14.9 for low dispersion. Over 104,000 ultraviolet spectra were obtained with IUE between January 26, 1978, and September 30, 1996.

The Far Ultraviolet Spectroscopic Explorer (FUSE), launched on June 24, 1999, covers the 905-1187 Å spectral region and will obtain high resolution spectra of hot and cool stars, AGNs, supernova remnants, planetary nebulae, solar system objects as well as perform detailed studies of the interstellar medium. FUSE will be able to observe sources 10 000 times fainter than Copernicus, an early FUV mission, and has superior resolving power than the Hopkins Ultraviolet Telescope (HUT) and the Berkeley Spectrograph (BEFS) and the Tübingen Echelle Spectrograph (TUES) of the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometers (ORFEUS). FUSE was planned for a 3 year lifetime with funding for an additional 2 years expected.

The Ultraviolet Imaging Telescope UIT was one of three ultraviolet telescopes on the ASTRO-1 mission flown on the space shuttle Columbia during 2-10 December 1990. The same three instruments were later flown on the space shuttle Endeavour from 3-17 March 1995, as part of the ASTRO-2 mission. Exposures were obtained on 70-mm photographic film in the 1200-3300 Å range using broadband filters and later digitized using a Perkin-Elmer microdensitometer. Image resolution was 3" over a 40' field of view. Overall, UIT-1 obtained 821 exposures of 66 targets, and UIT-2 obtained 758 images of 193 targets.

This describes the data produce for ICON EUV Daytime O+ (DP 2.6), which is in NetCDF4 format. These files are named ICON_L2-6_EUV_YYYY-MM-DD_vXXrZZ.NC, where YYYY-MM-DD is the year month day and VXX shows the version number and rZZ shows the revision number of this file. Each individual file nominally contains 1 day (24 hours) of data. The L2 EUV Daytime files are produced from the L1 EUV files, and their primary data product is the O+ profile derived from a retrieval that is detailed in a paper: https://doi.org/10.1007/s11214-017-0385-1. In addition, many other parameters and geophysical data products are included in the file. The data are identified in one of 3 var_types: data – which contains the primary data product; support data – which contains parameters used in the retrieval such as geometry etc. that may also be useful in any analysis of this data; and ignore_data – which are recorded for debugging purposes and should not be used for publication without detailed discussion with the ICON team. The dimensions of the data also indicate its type. For example, anything with epoch as a dimension means there is 1 value corresponding to each instrument exposure. Anything with dimension Input_data corresponds to the input data, passed from Level 1. Anything with a dimension of model refers to the forward model parameters used as part of the inversion. Anything with dimension altitude corresponds to the altitude grid used for the inverted parameters.