IUE has been the most productive astronomical telescope ever. Its 18.7 years of operations returned 104 470 high- and low-resolution images of 9600 astronomical sources from all classes of celestial objects in the ultraviolet band.
These images were transformed into 111 000 spectral files now collected together and accessible world-wide through national hosts with ESA's INES system, which is operated for the astronomical community by the Laboratory for Space Astrophysics and Theoretical Physics (LAEFF) in Spain, in close collaboration with the Canadian Astronomical Data centre (CADC) in Victoria. An IUE archival site, under the Multimission Archive at the Space Telescope Science Institute (STScI) in Baltimore, is maintained by NASA. IUE provided astronomers with a unique tool and demand for observation time remained two to three times greater than could be satisfied, even at the end of orbital operations.
Despite the appearance of the Hubble Space Telescope (HST) in 1990, IUE continued to prosper because it covered the entire spectral region in ways not possible with HST's high-resolution spectrographs in low Earth orbit. The combination of IUE and HST provided a very efficient complementary function for astronomers.