In-orbit Performance of NASA's Extreme Ultraviolet Explorer Observatory

NASA's Extreme Ultraviolet Explorer was launched on June 7, 1992. The payload includes four grazing incidence EUV telescopes with imaging microchannel plate detectors. Three of the telescopes have been used to make an all-sky survey in four wavelength bands at 100 Angstroms, 200 Angstroms, 450 Angstroms and 600 Angstroms. The fourth telescope, the Deep Survey/Spectrometer, has been used to carry out a deep survey of approximately 1% of the sky. This instrument, now being operated as a Guest Observer facility to carry out spectroscopic observations of EUV sources, has a resolving power of lambda /Delta lambda ~ 300 from 70--760 Angstroms. The spacecraft and all instruments have all been working flawlessly since launch and the in-orbit data are excellent. In this paper we describe the in-orbit performance of the instruments, the in-orbit calibration, and the sensitivities achieved by the surveys. This work has been supported by NASA contract NAS5-29298.