GOES 4

About This Satellite

GOES-4 introduced the first VISSR Atmospheric Sounder, or VAS, to geosynchronous orbit in September 1980. The experimental instrument added atmospheric sounding to repeated weather observation from that orbit. Researchers could investigate temperature and water-vapor structure as well as cloud patterns, rather than relying on cloud appearance alone.

Repeated spectral observations revealed changing atmospheric structure

The Wisconsin mission history describes multispectral observations of temperature, water vapor, and cloudiness over short intervals. The scientific gain came from comparing information across spectral bands and time. A coloured weather image is only one possible display of those observations; it should not be mistaken for a literal photograph of separate atmospheric layers.

The ground-processing work was part of the experiment

The University of Wisconsin team participated in instrument development, operations, analysis, and processing. Turning VAS observations into useful weather information therefore required more than a successful launch. GOES-5 and GOES-6 subsequently carried VAS instruments, but their individual observations and operating histories remain separate from GOES-4's record.

Mission reference: University of Wisconsin SSEC: GOES-4 and the experimental VAS sounder. Editorial review: 2026-09-14.

Imaging and sounding competed for the same optics

NOAA describes GOES-4 through GOES-7 as spin-stabilized spacecraft whose imaging and sounding functions shared an optical system and had to take turns. This limited the combination of observations available at one instant. The later GOES-8 generation separated the optics and adopted three-axis stabilization. Those later capabilities should not be assigned to GOES-4 merely because both generations belonged to the GOES programme.

Reference: NOAA NESDIS: shared optics on GOES D-H and the later GOES I-M design.

The space-weather archive records a system failure

NOAA NCEI's instrument-availability table lists GOES-4 with a system failure and no available Space Environment Monitor instruments. This is an important exception to descriptions of the broader GOES family. Successful atmospheric sounding does not demonstrate that a different instrument subsystem worked. Do not attribute neighbouring satellites' particle, magnetic-field, or solar X-ray measurements to GOES-4 to fill this gap.

Reference: NOAA NCEI: GOES-4 Space Environment Monitor system-failure entry.

An imagery archive is a collection, not a complete mission clock

NOAA CLASS lists primary GOES-4 imagery from March 5, 1981 through November 26, 1982, with an approximate operational subpoint at 135 degrees west. These fields describe that archive and observing context. They are not a present-day longitude, an exact spacecraft shutdown date, or evidence that every observation made during the mission is included in that particular collection.

Reference: NOAA CLASS: GOES-4 primary-imager archive coverage and approximate position.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 35,947 km at perigee to 36,213 km at apogee, a difference of 266 km. The orbital period is about 1451.1 minutes. Eccentricity 0.00313 indicates a nearly circular path. In a two-body approximation, perigee speed is 1.01 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 7.82 degrees implies approximate geocentric ground-track limits of 7.8 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 1451.1 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 11964 · GCAT: S11964 (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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