EXOSAT

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EXOSAT

EXOSAT
Mission type	Astronomy
Operator	ESA
COSPAR ID	1983-051A
SATCAT no.	14095
Website	www.esa.int/export/esaSC/120394_index_0_m.html
Mission duration	3 years
Spacecraft properties
Manufacturer	MBB
Launch mass	510.0 kg (1,124.4 lb)
Power	165.0 watts
Start of mission
Launch date	26 May 1983, 15:18:00 (1983-05-26UTC15:18Z) UTC
Rocket	Delta 3914 D169
Launch site	Vandenberg SLC-2W
End of mission
Decay date	5 May 1986 (1986-05-06)
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Eccentricity	0.93428
Perigee altitude	347 km (216 mi)
Apogee altitude	191,709 km (119,122 mi)
Inclination	72.5 degrees
Period	5,435.4 minutes
Epoch	26 May 1983, 11:18:00 UTC[1]
Legacy ESA insignia for the EXOSAT mission

The European X-ray Observatory Satellite (EXOSAT), originally named HELOS, was an X-ray telescope operational from May 1983 until April 1986 and in that time made 1780 observations in the X-ray band of most classes of astronomical object including active galactic nuclei, stellar coronae, cataclysmic variables, white dwarfs, X-ray binaries, clusters of galaxies, and supernova remnants.

This European Space Agency (ESA) satellite for direct-pointing and lunar-occultation observation of X-ray sources beyond the Solar System was launched into a highly eccentric orbit (apogee 200,000 km, perigee 500 km) almost perpendicular to that of the Moon on 26 May 1983. The instrumentation includes two low-energy imaging telescopes (LEIT) with Wolter I X-ray optics (for the 0.04–2 keV energy range), a medium-energy experiment using Ar/CO₂ and Xe/CO₂ detectors (for 1.5–50 keV), a Xe/He gas scintillation spectrometer (GSPC) (covering 2–80 keV), and a reprogrammable onboard data-processing computer. Exosat was capable of observing an object (in the direct-pointing mode) for up to 80 hours and of locating sources to within at least 10 arcsec with the LEIT and about 2 arcsec with GSPC.^[2]