XMM

About This Satellite

XMM-Newton is an ESA X-ray observatory with three X-ray telescopes and a complementary optical/ultraviolet telescope. Its observations probe high-energy astronomical sources. The XMM catalog label identifies the observatory itself; a location over Earth does not identify the black hole, star, or galaxy being observed.

Cameras and spectrometers reveal different properties

The EPIC cameras record X-ray images and energy information. Reflection Grating Spectrometers separate wavelengths more finely, helping astronomers study the emitting material. The Optical Monitor provides simultaneous observations in a different part of the spectrum. These instruments combine complementary evidence instead of producing several versions of the same ordinary photograph.

The orbit is not the telescope pointing direction

The ground track tells you where a line from Earth's centre through the spacecraft meets the surface. It does not show the observatory's astronomical field of view. A target can be very far from that direction; observations depend on pointing plans and spacecraft constraints, not simply on which country lies underneath.

Mission reference: ESA: XMM-Newton factsheet. Editorial review: 2026-09-07.

Why a highly elliptical orbit is useful

ESA describes XMM-Newton's approximately 48-hour orbit as enabling long observations. The spacecraft spends much of an elliptical orbit far from Earth, unlike a low-orbit telescope that repeatedly encounters Earth occultations. Treat the quoted period as mission context and compare it with the dated values below; the track is not a constant-speed circuit.

Reference: ESA Operations: XMM-Newton orbit and observations.

Why the X-ray mirrors are nested shells

Each of the three X-ray telescopes contains 58 nested grazing-incidence mirror shells. X-rays are focused by shallow-angle reflections, rather than by copying the normal mirror geometry of a visible-light telescope. Nesting many shells increases collecting area within the telescope structure, helping detect faint sources without treating the spacecraft as one enormous conventional dish.

Reference: ESA: XMM-Newton mirror design.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-06. Estimated altitude ranges from 29,422 km at perigee to 91,707 km at apogee, a difference of 62,285 km. The orbital period is about 2872.9 minutes. Eccentricity 0.46521 shows why a single altitude cannot describe the whole path. In a two-body approximation, perigee speed is 2.74 times apogee speed. These are mean-element estimates, not instantaneous measurements. Distance per orbit uses an ellipse approximation.

Saved build snapshot. If a valid TLE is retrieved, this explanation and the orbit panel update together. Otherwise this dated snapshot is retained.

Ground track is not sensor coverage

An inclination of 64.06 degrees implies approximate geocentric ground-track limits of 64.1 degrees north and south. This is a prograde orbit, moving in the same general direction as Earth rotation. The plotted line marks the point beneath the object. It does not represent camera coverage, radio reception, or a guaranteed visible pass.

Is it fixed above one longitude?

The snapshot period is 2872.9 minutes. A sidereal day is about 1,436.07 minutes. Height alone does not establish a geostationary orbit: the period must match Earth rotation and the path must be circular and equatorial. This catalog uses a five-minute period tolerance for near-geosynchronous labels; near-geostationary additionally requires inclination at most 1 degree and eccentricity at most 0.01. These are browsing categories, not evidence of station-keeping or a fixed longitude.

Accuracy and missing information

The introductory record describes the build snapshot. The orbital snapshot explanation and orbit panel share any successfully retrieved TLE; check the displayed epoch. Reentered objects retain historical data only. Mission history is not rewritten by TLE updates. TLE/SGP4 positions are predictions and can change after maneuvers or updated observations. The 14-day stale-data cutoff is a display safeguard, not an accuracy guarantee. Local passes are geometric predictions, not a visibility forecast. No verified operator or mission status means unknown, not active. Do not use this catalog for collision avoidance or operational flight decisions.

Catalog sources: CelesTrak SATCAT: NORAD 25989 · GCAT: S25989 (source update 2026 Sep 4 2345:57). Supplementary metadata: SatNOGS DB, retrieved 2026-09-05T12:57:25.375Z. Page assembled 2026-09-15. GCAT phase codes describe trajectory phases, not mission health.

Learn more: TLE data · Perigee and apogee · Ground tracks · JOT (Jewawud Live Orbital Map)

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