XMM-Newton Users Handbook

4.1 XMM-Newton orbit

XMM-Newton was launched on the 10th December 1999 by an Ariane 5 launcher into a highly elliptical orbit, with an apogee of about 115,000 km and a perigee of ca. 6000 km (Fig. 120). XMM-Newton is operated with three ground stations, located at Yatharagga, Kourou and Santiago de Chile (occasionally also ESAC, Madrid, Spain).

**Figure 120:** *Sketch of the highly elliptical XMM-Newton orbit. Original figure provided by Dornier Satellitensysteme GmbH.*
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Due to several perturbations, the orbit of XMM-Newton changes with time. In addition, an orbit correction manoeuvre was performed in February 2003 to ensure full ground station coverage during the entire science period. The orbital parameters for May 2022 are listed in Table 29. Such an orbit provides the best visibility in the southern celestial sky (§ 4.2.3).

**Table 29:** *Evolution of Orbital Parameters of XMM-Newton*
	May 2023	May 2025	May 2027	unit
Inclination	69.0	66.3	63.7	$^\circ$
Right ascension of ascending node	298.9	288.0	280.3	$^\circ$
Argument of perigee	82.9	72.2	61.1	$^\circ$
Apogee height	98.3	93.3	91.4	10 km
Perigee height	22.8	27.8	29.7	10 km
Eccentricity	0.56	0.49	0.46
Period	47.87	47.86	47.87	hours

European Space Agency - XMM-Newton Science Operations Centre