PM1EPHND: Aqua Satellite Near-Real-Time Ephemeris Data for Geolocation

PM1EPHND files contain Aqua satellite definitive ephemeris data in a native binary format, processed for Near Real Time (NRT) delivery. The data is MODIS ancillary information used for determining the geolocation of Earth remote sensing observations. The National Aeronautics and Space Administration (NASA) produces this data, with files named according to a versioned convention including acquisition year, Julian day, hour, and minute.

Use Cases

• Correcting satellite image geolocation based on definitive spacecraft position and attitude data.
• Calibrating remote sensing observation coordinates using the preprocessed ephemeris information.
• Supporting Near Real Time (NRT) data processing pipelines that require precise orbital parameters.

Strengths

• Data is processed to an internal standard supported by the ECS SDP Toolkit, suggesting a defined format.
• Files follow a consistent naming convention (PM1EPHND_NRT.Ayyyyddd.hhmm.vvv) that encodes acquisition time and version.
• Data is designated as 'definitive' and for Near Real Time use, implying a specific processing level.

Limitations

• Column-level documentation is absent; field semantics and data structure must be inferred after download.
• Row count and total dataset size are unknown, which may limit suitability assessment.
• Data is in a proprietary binary (BIN) format requiring the specific SDP Toolkit for interpretation.

Provenance

Source

National Aeronautics and Space Administration

Collection Method

Preprocessed by ECS (EOSDIS Core System) from Aqua spacecraft attitude data.

Time Range

Coverage is implied by file naming convention (year, Julian day).

Freshness

Last updated 2026-03-12 23:54:04.218033; freshness should be verified.

Geography

Global, as the data supports geolocation for Earth remote sensing observations.