# Orbis v0.9.1 - Table of Contents

Satellite toolkit for Elixir — SGP4 propagation, coordinate transforms
(0 ULP Skyfield parity), GNSS positioning, orbit determination, conjunction
assessment, pass prediction, live TLE/OMM data, and real-time tracking.
Rust NIF backend.

## Pages

- [README](readme.md)
- [Changelog](changelog.md)
- [ISS Tracker](iss_tracker.md)
- [GNSS Positioning](gnss_positioning.md)

- Guides
  - [Track the ISS from a Ground Station](track_iss.md)
  - [Predict Passes with Doppler](pass_prediction.md)
  - [Conjunction Screening](conjunction_screening.md)
  - [Accuracy &amp; Validation](accuracy.md)
  - [Batch Analysis: Coverage, Visibility, and Link Budgets at Scale](batch_analysis.md)
  - [GNSS Constellation Catalogs](gnss_constellation_catalog.md)

## Modules

- [Orbis.CCSDS.CDM](Orbis.CCSDS.CDM.md): Parse and encode CCSDS Conjunction Data Messages (CDM).
- [Orbis.CCSDS.CDM.ObjectData](Orbis.CCSDS.CDM.ObjectData.md): Object-specific data block inside a parsed CCSDS CDM.

- [Orbis.Collision](Orbis.Collision.md): Collision probability calculation for close approaches.
- [Orbis.Collision.Result](Orbis.Collision.Result.md): Result of a collision-probability evaluation.

- [Orbis.Covariance](Orbis.Covariance.md): Covariance matrix helpers for conjunction and orbit analysis.
- [Orbis.Encounter](Orbis.Encounter.md): Encounter geometry helpers for conjunction assessment.
- [Orbis.Encounter.Frame](Orbis.Encounter.Frame.md): Relative encounter geometry at a common epoch.
- [Orbis.Forces.J2](Orbis.Forces.J2.md): Earth's oblateness (J2) perturbation force model.

- [Orbis.Forces.TwoBody](Orbis.Forces.TwoBody.md): Standard Keplerian Two-Body gravity force model.

- [Orbis.GNSS.CarrierPhase](Orbis.GNSS.CarrierPhase.md): Dual-frequency carrier-phase linear combinations and the precise-positioning
prep tooling built on them: geometry-free and wide-lane phase, the
narrow-lane code, Melbourne-Wubbena, cycle-slip detection, and Hatch
carrier-smoothed code.
- [Orbis.GNSS.Constellation.NavcenStatus](Orbis.GNSS.Constellation.NavcenStatus.md): A parsed row from NAVCEN's GPS constellation status table.

- [Orbis.GNSS.Constellation.Record](Orbis.GNSS.Constellation.Record.md): A normalized GNSS satellite identity record.
- [Orbis.GNSS.Constellation.Validation](Orbis.GNSS.Constellation.Validation.md): Validation report for a GNSS constellation catalog.

- [Orbis.GNSS.Positioning.Solution](Orbis.GNSS.Positioning.Solution.md): A single-point-positioning solution at one receive epoch.
- [Orbis.GNSS.SP3.State](Orbis.GNSS.SP3.State.md): An interpolated SP3 satellite state at one epoch.
- [Orbis.Geodetic](Orbis.Geodetic.md): WGS84 geodetic position: latitude, longitude, altitude.

- [Orbis.LookAngle](Orbis.LookAngle.md): Topocentric look angle from a ground station to a satellite.

- [Orbis.Pass](Orbis.Pass.md): A satellite pass over a ground station.

- [Orbis.Propagator](Orbis.Propagator.md): High-precision numerical orbit propagation.
- [Orbis.Screening](Orbis.Screening.md): Catalog-scale conjunction screening.
- [Orbis.Screening.Candidate](Orbis.Screening.Candidate.md): A prefiltered conjunction candidate from catalog screening.

- [Orbis.Screening.Result](Orbis.Screening.Result.md): Final result for a screened candidate pair.

- [Orbis.TLE](Orbis.TLE.md): Backwards-compatible delegates for TLE/OMM parsing.

- Core
  - [Orbis](Orbis.md): Satellite toolkit for Elixir. SGP4 orbit propagation, coordinate
transformations, and ground station pass prediction.

  - [Orbis.Elements](Orbis.Elements.md): Canonical representation of satellite orbital elements.
  - [Orbis.SGP4](Orbis.SGP4.md): SGP4/SDP4 orbit propagation from Two-Line Element sets.

  - [Orbis.TemeState](Orbis.TemeState.md): Represents the position and velocity of a satellite in the TEME coordinate system.

- Coordinates
  - [Orbis.Coordinates](Orbis.Coordinates.md): Coordinate frame transformations for satellite state vectors.

- Ground Station
  - [Orbis.Doppler](Orbis.Doppler.md): Doppler shift calculation for satellite-ground links.
  - [Orbis.Passes](Orbis.Passes.md): Satellite pass prediction over a ground station.
  - [Orbis.RF](Orbis.RF.md): RF link budget primitives.
  - [Orbis.Tracker](Orbis.Tracker.md): Real-time satellite position tracker.

- Orbit Determination
  - [Orbis.IOD](Orbis.IOD.md): Initial Orbit Determination methods.
  - [Orbis.Lambert](Orbis.Lambert.md): Lambert problem solver (Battin's method).

- Space Environment
  - [Orbis.Angles](Orbis.Angles.md): Angular geometry calculations for satellites.
  - [Orbis.Atmosphere](Orbis.Atmosphere.md): Atmospheric density via the NRLMSISE-00 empirical model.
  - [Orbis.Eclipse](Orbis.Eclipse.md): Earth shadow (eclipse) prediction for satellites.
  - [Orbis.Ephemeris](Orbis.Ephemeris.md): JPL SPK/BSP ephemeris file reader.

- Conjunction
  - [Orbis.Conjunction](Orbis.Conjunction.md): Find close approaches between two satellites.

- GNSS Positioning
  - [Orbis.GNSS.Broadcast](Orbis.GNSS.Broadcast.md): A parsed RINEX broadcast-navigation product (GPS LNAV, Galileo I/NAV+F/NAV,
BeiDou D1/D2, GLONASS).
  - [Orbis.GNSS.Constellation](Orbis.GNSS.Constellation.md): GNSS constellation identity catalogs and validation helpers.
  - [Orbis.GNSS.DGNSS](Orbis.GNSS.DGNSS.md): Code-differential GNSS (DGPS) positioning over single-frequency pseudoranges.
  - [Orbis.GNSS.Geometry](Orbis.GNSS.Geometry.md): Satellite-geometry and mission-planning layer above the GNSS observables:
from a static receiver position and a precise (SP3) ephemeris, answer the
three planning questions — which satellites are visible, how good is the
geometry (dilution of precision), and when does each satellite rise and set.
  - [Orbis.GNSS.Ionosphere](Orbis.GNSS.Ionosphere.md): Single-frequency ionospheric group-delay corrections.
  - [Orbis.GNSS.IonosphereFree](Orbis.GNSS.IonosphereFree.md): The dual-frequency ionosphere-free linear combination of pseudoranges.
  - [Orbis.GNSS.Navigation.LNAV](Orbis.GNSS.Navigation.LNAV.md): GPS L1 C/A LNAV navigation message synthesis and decoding (subframes 1-3).
  - [Orbis.GNSS.Navigation.LNAV.Ephemeris](Orbis.GNSS.Navigation.LNAV.Ephemeris.md): GPS LNAV clock and ephemeris parameters in engineering units.
  - [Orbis.GNSS.Observables](Orbis.GNSS.Observables.md): Predict the GNSS observables a receiver at a known ECEF position would see for
a satellite, from a precise (SP3) ephemeris source.
  - [Orbis.GNSS.Positioning](Orbis.GNSS.Positioning.md): GNSS single-point positioning (SPP): recover a receiver position, clock bias,
and geometry diagnostics from one epoch of pseudorange observations against a
precise SP3 ephemeris or a broadcast navigation product.
  - [Orbis.GNSS.QC](Orbis.GNSS.QC.md): Measurement-quality control for single-point positioning: a generic
"is this measurement set self-consistent?" layer over
`Orbis.GNSS.Positioning`.
  - [Orbis.GNSS.RINEX.Observations](Orbis.GNSS.RINEX.Observations.md): RINEX 3 observation products: parse a station's observation file, expose its
header (including the surveyed `APPROX POSITION XYZ`), and extract the
single-frequency pseudoranges that `Orbis.GNSS.Positioning.solve/4` consumes.
  - [Orbis.GNSS.ReducedOrbit](Orbis.GNSS.ReducedOrbit.md): A compact, fitted mean-element approximation of a satellite's orbit.
  - [Orbis.GNSS.ReducedOrbit.Piecewise](Orbis.GNSS.ReducedOrbit.Piecewise.md): A long position track approximated by a sequence of contiguous, independently
fitted `Orbis.GNSS.ReducedOrbit` segments.
  - [Orbis.GNSS.SP3](Orbis.GNSS.SP3.md): SP3-c / SP3-d precise-ephemeris products (IGS precise orbits + clocks).
  - [Orbis.GNSS.Signal.CA](Orbis.GNSS.Signal.CA.md): GPS L1 coarse/acquisition (C/A) code generation and correlation.
  - [Orbis.GNSS.Signal.Correlator](Orbis.GNSS.Signal.Correlator.md): Baseband simulation, correlation, and acquisition for the GPS L1 C/A signal.
  - [Orbis.GNSS.SolutionReport](Orbis.GNSS.SolutionReport.md): A consolidated, read-only diagnostic for a single-point-positioning result.
  - [Orbis.GNSS.Time](Orbis.GNSS.Time.md): Epoch conversions shared by the GNSS correction wrappers.
  - [Orbis.GNSS.Troposphere](Orbis.GNSS.Troposphere.md): Neutral-atmosphere (tropospheric) signal-delay corrections.
  - [Orbis.GNSS.Velocity](Orbis.GNSS.Velocity.md): Recover a receiver's velocity and clock drift from one epoch of Doppler or
pseudorange-rate measurements against a precise (SP3) ephemeris source.

- Data Sources
  - [Orbis.CelesTrak](Orbis.CelesTrak.md): Fetch TLEs and orbital data from CelesTrak.
  - [Orbis.Constellation](Orbis.Constellation.md): Manage and propagate satellite constellations.
  - [Orbis.GNSS.Data](Orbis.GNSS.Data.md): Optional fetch-and-cache layer for GNSS products (SP3, RINEX clock, broadcast
navigation, IONEX).
  - [Orbis.GNSS.Data.Cache](Orbis.GNSS.Data.Cache.md): Local, on-disk cache for decompressed GNSS products, with atomic writes,
SHA-256 integrity, gzip decompression (with a bomb guard), and a JSON
provenance sidecar.
  - [Orbis.GNSS.Data.Catalog](Orbis.GNSS.Data.Catalog.md): Static, pure catalog of GNSS analysis centers and the rules that turn a
product specification into a canonical filename and a full archive URL.
  - [Orbis.GNSS.Data.Product](Orbis.GNSS.Data.Product.md): A GNSS product specification: the analysis center, content type, calendar
date, and temporal sampling that together identify one archived file.

- Batch Analysis
  - [Orbis.Nx](Orbis.Nx.md): Batch/tensor analysis helpers for Orbis.
  - [Orbis.Nx.Coverage](Orbis.Nx.Coverage.md): Higher-level batched access and coverage metrics.

  - [Orbis.Nx.Geometry](Orbis.Nx.Geometry.md): Tensorized geometry helpers.
  - [Orbis.Nx.RF](Orbis.Nx.RF.md): Tensorized RF helpers for large access and coverage studies.

  - [Orbis.Nx.Visibility](Orbis.Nx.Visibility.md): Tensorized visibility products built on top of `Orbis.Nx.Geometry`.

- Format
  - [Orbis.Format.OMM](Orbis.Format.OMM.md): Parse and encode CCSDS Orbit Mean-Elements Messages (OMM).
  - [Orbis.Format.TLE](Orbis.Format.TLE.md): Parse and encode Two-Line Element sets.

