Struct Epoch

#[repr(C)]
pub struct Epoch {
    pub duration: Duration,
    pub time_scale: TimeScale,
}

Defines a nanosecond-precision Epoch.

Refer to the appropriate functions for initializing this Epoch from different time scales or representations.

(Python documentation hints) :type string_repr: str :rtype: Epoch

Fields

duration: Duration

An Epoch is always stored as the duration since the beginning of its time scale

time_scale: TimeScale

Time scale used during the initialization of this Epoch.

Implementations

impl Epoch

pub fn to_gregorian_str(&self, time_scale: TimeScale) -> String

Converts the Epoch to Gregorian in the provided time scale and in the ISO8601 format with the time scale appended to the string

pub fn to_gregorian_utc(&self) -> (i32, u8, u8, u8, u8, u8, u32)

Converts the Epoch to the Gregorian UTC equivalent as (year, month, day, hour, minute, second). WARNING: Nanoseconds are lost in this conversion!

Example

use hifitime::Epoch;

let dt_tai = Epoch::from_tai_parts(1, 537582752000000000);

let dt_str = "2017-01-14T00:31:55 UTC";
let dt = Epoch::from_gregorian_str(dt_str).unwrap();

let (y, m, d, h, min, s, _) = dt_tai.to_gregorian_utc();
assert_eq!(y, 2017);
assert_eq!(m, 1);
assert_eq!(d, 14);
assert_eq!(h, 0);
assert_eq!(min, 31);
assert_eq!(s, 55);
#[cfg(feature = "std")]
{
assert_eq!("2017-01-14T00:31:55 UTC", format!("{dt_tai:?}"));
// dt_tai is initialized from TAI, so the default print is the Gregorian in that time system
assert_eq!("2017-01-14T00:32:32 TAI", format!("{dt_tai}"));
// But dt is initialized from UTC, so the default print and the debug print are both in UTC.
assert_eq!("2017-01-14T00:31:55 UTC", format!("{dt}"));
}

pub fn to_gregorian_tai(&self) -> (i32, u8, u8, u8, u8, u8, u32)

Converts the Epoch to the Gregorian TAI equivalent as (year, month, day, hour, minute, second). WARNING: Nanoseconds are lost in this conversion!

Example

use hifitime::Epoch;
let dt = Epoch::from_gregorian_tai_at_midnight(1972, 1, 1);
let (y, m, d, h, min, s, _) = dt.to_gregorian_tai();
assert_eq!(y, 1972);
assert_eq!(m, 1);
assert_eq!(d, 1);
assert_eq!(h, 0);
assert_eq!(min, 0);
assert_eq!(s, 0);

pub fn maybe_from_gregorian_tai( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, nanos: u32, ) -> Result<Epoch, HifitimeError>

Attempts to build an Epoch from the provided Gregorian date and time in TAI.

pub fn maybe_from_gregorian( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, nanos: u32, time_scale: TimeScale, ) -> Result<Epoch, HifitimeError>

Attempts to build an Epoch from the provided Gregorian date and time in the provided time scale.

Note: The month is ONE indexed, i.e. January is month 1 and December is month 12.

pub fn from_gregorian_tai( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, nanos: u32, ) -> Epoch

Builds an Epoch from the provided Gregorian date and time in TAI. If invalid date is provided, this function will panic. Use maybe_from_gregorian_tai if unsure.

pub fn from_gregorian_tai_at_midnight(year: i32, month: u8, day: u8) -> Epoch

Initialize from the Gregorian date at midnight in TAI.

pub fn from_gregorian_tai_at_noon(year: i32, month: u8, day: u8) -> Epoch

Initialize from the Gregorian date at noon in TAI

pub fn from_gregorian_tai_hms( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, ) -> Epoch

Initialize from the Gregorian date and time (without the nanoseconds) in TAI

pub fn maybe_from_gregorian_utc( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, nanos: u32, ) -> Result<Epoch, HifitimeError>

Attempts to build an Epoch from the provided Gregorian date and time in UTC.

pub fn from_gregorian_utc( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, nanos: u32, ) -> Epoch

Builds an Epoch from the provided Gregorian date and time in UTC. If invalid date is provided, this function will panic. Use maybe_from_gregorian_utc if unsure.

pub fn from_gregorian_utc_at_midnight(year: i32, month: u8, day: u8) -> Epoch

Initialize from Gregorian date in UTC at midnight

pub fn from_gregorian_utc_at_noon(year: i32, month: u8, day: u8) -> Epoch

Initialize from Gregorian date in UTC at noon

pub fn from_gregorian_utc_hms( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, ) -> Epoch

Initialize from the Gregorian date and time (without the nanoseconds) in UTC

Examples found in repository

examples/03_geo_analysis/stationkeeping.rs (line 32)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();
    // Set up the dynamics like in the orbit raise.
    let almanac = Arc::new(MetaAlmanac::latest().map_err(Box::new)?);
    let epoch = Epoch::from_gregorian_utc_hms(2024, 2, 29, 12, 13, 14);

    // Define the GEO orbit, and we're just going to maintain it very tightly.
    let earth_j2000 = almanac.frame_from_uid(EARTH_J2000)?;
    let orbit = Orbit::try_keplerian(42164.0, 1e-5, 0., 163.0, 75.0, 0.0, epoch, earth_j2000)?;
    println!("{orbit:x}");

    let sc = Spacecraft::builder()
        .orbit(orbit)
        .dry_mass_kg(1000.0) // 1000 kg of dry mass
        .fuel_mass_kg(1000.0) // 1000 kg of fuel, totalling 2.0 tons
        .srp(SrpConfig::from_area(3.0 * 6.0)) // Assuming 1 kW/m^2 or 18 kW, giving a margin of 4.35 kW for on-propulsion consumption
        .thruster(Thruster {
            // "NEXT-STEP" row in Table 2
            isp_s: 4435.0,
            thrust_N: 0.472,
        })
        .mode(GuidanceMode::Thrust) // Start thrusting immediately.
        .build();

    // Set up the spacecraft dynamics like in the orbit raise example.

    let prop_time = 30.0 * Unit::Day;

    // Define the guidance law -- we're just using a Ruggiero controller as demonstrated in AAS-2004-5089.
    let objectives = &[
        Objective::within_tolerance(StateParameter::SMA, 42_164.0, 5.0), // 5 km
        Objective::within_tolerance(StateParameter::Eccentricity, 0.001, 5e-5),
        Objective::within_tolerance(StateParameter::Inclination, 0.05, 1e-2),
    ];

    let ruggiero_ctrl = Ruggiero::from_max_eclipse(objectives, sc, 0.2)?;
    println!("{ruggiero_ctrl}");

    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![MOON, SUN]);

    let mut jgm3_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/JGM3.cof.gz".to_string(),
        crc32: Some(0xF446F027), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    jgm3_meta.process(true)?;

    let harmonics = Harmonics::from_stor(
        almanac.frame_from_uid(IAU_EARTH_FRAME)?,
        HarmonicsMem::from_cof(&jgm3_meta.uri, 8, 8, true)?,
    );
    orbital_dyn.accel_models.push(harmonics);

    let srp_dyn = SolarPressure::default(EARTH_J2000, almanac.clone())?;
    let sc_dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn)
        .with_guidance_law(ruggiero_ctrl.clone());

    println!("{sc_dynamics}");

    // Finally, let's use the Monte Carlo framework built into Nyx to propagate spacecraft.

    // Let's start by defining the dispersion.
    // The MultivariateNormal structure allows us to define the dispersions in any of the orbital parameters, but these are applied directly in the Cartesian state space.
    // Note that additional validation on the MVN is in progress -- https://github.com/nyx-space/nyx/issues/339.
    let mc_rv = MvnSpacecraft::new(
        sc,
        vec![StateDispersion::zero_mean(StateParameter::SMA, 3.0)],
    )?;

    let my_mc = MonteCarlo::new(
        sc, // Nominal state
        mc_rv,
        "03_geo_sk".to_string(), // Scenario name
        None, // No specific seed specified, so one will be drawn from the computer's entropy.
    );

    // Build the propagator setup.
    let setup = Propagator::rk89(
        sc_dynamics.clone(),
        IntegratorOptions::builder()
            .min_step(10.0_f64.seconds())
            .error_ctrl(ErrorControl::RSSCartesianStep)
            .build(),
    );

    let num_runs = 25;
    let rslts = my_mc.run_until_epoch(setup, almanac.clone(), sc.epoch() + prop_time, num_runs);

    assert_eq!(rslts.runs.len(), num_runs);

    // For all of the resulting trajectories, we'll want to compute the percentage of penumbra and umbra.

    rslts.to_parquet(
        "03_geo_sk.parquet",
        Some(vec![
            &EclipseLocator::cislunar(almanac.clone()).to_penumbra_event()
        ]),
        ExportCfg::default(),
        almanac,
    )?;

    Ok(())
}

examples/03_geo_analysis/raise.rs (line 43)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();

    // Dynamics models require planetary constants and ephemerides to be defined.
    // Let's start by grabbing those by using ANISE's latest MetaAlmanac.
    // This will automatically download the DE440s planetary ephemeris,
    // the daily-updated Earth Orientation Parameters, the high fidelity Moon orientation
    // parameters (for the Moon Mean Earth and Moon Principal Axes frames), and the PCK11
    // planetary constants kernels.
    // For details, refer to https://github.com/nyx-space/anise/blob/master/data/latest.dhall.
    // Note that we place the Almanac into an Arc so we can clone it cheaply and provide read-only
    // references to many functions.
    let almanac = Arc::new(MetaAlmanac::latest().map_err(Box::new)?);
    // Fetch the EME2000 frame from the Almabac
    let eme2k = almanac.frame_from_uid(EARTH_J2000).unwrap();
    // Define the orbit epoch
    let epoch = Epoch::from_gregorian_utc_hms(2024, 2, 29, 12, 13, 14);

    // Build the spacecraft itself.
    // Using slide 6 of https://aerospace.org/sites/default/files/2018-11/Davis-Mayberry_HPSEP_11212018.pdf
    // for the "next gen" SEP characteristics.

    // GTO start
    let orbit = Orbit::keplerian(24505.9, 0.725, 7.05, 0.0, 0.0, 0.0, epoch, eme2k);

    let sc = Spacecraft::builder()
        .orbit(orbit)
        .dry_mass_kg(1000.0) // 1000 kg of dry mass
        .fuel_mass_kg(1000.0) // 1000 kg of fuel, totalling 2.0 tons
        .srp(SrpConfig::from_area(3.0 * 6.0)) // Assuming 1 kW/m^2 or 18 kW, giving a margin of 4.35 kW for on-propulsion consumption
        .thruster(Thruster {
            // "NEXT-STEP" row in Table 2
            isp_s: 4435.0,
            thrust_N: 0.472,
        })
        .mode(GuidanceMode::Thrust) // Start thrusting immediately.
        .build();

    let prop_time = 180.0 * Unit::Day;

    // Define the guidance law -- we're just using a Ruggiero controller as demonstrated in AAS-2004-5089.
    let objectives = &[
        Objective::within_tolerance(StateParameter::SMA, 42_165.0, 20.0),
        Objective::within_tolerance(StateParameter::Eccentricity, 0.001, 5e-5),
        Objective::within_tolerance(StateParameter::Inclination, 0.05, 1e-2),
    ];

    // Ensure that we only thrust if we have more than 20% illumination.
    let ruggiero_ctrl = Ruggiero::from_max_eclipse(objectives, sc, 0.2).unwrap();
    println!("{ruggiero_ctrl}");

    // Define the high fidelity dynamics

    // Set up the spacecraft dynamics.

    // Specify that the orbital dynamics must account for the graviational pull of the Moon and the Sun.
    // The gravity of the Earth will also be accounted for since the spaceraft in an Earth orbit.
    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![MOON, SUN]);

    // We want to include the spherical harmonics, so let's download the gravitational data from the Nyx Cloud.
    // We're using the JGM3 model here, which is the default in GMAT.
    let mut jgm3_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/JGM3.cof.gz".to_string(),
        crc32: Some(0xF446F027), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    // And let's download it if we don't have it yet.
    jgm3_meta.process(true)?;

    // Build the spherical harmonics.
    // The harmonics must be computed in the body fixed frame.
    // We're using the long term prediction of the Earth centered Earth fixed frame, IAU Earth.
    let harmonics = Harmonics::from_stor(
        almanac.frame_from_uid(IAU_EARTH_FRAME)?,
        HarmonicsMem::from_cof(&jgm3_meta.uri, 8, 8, true).unwrap(),
    );

    // Include the spherical harmonics into the orbital dynamics.
    orbital_dyn.accel_models.push(harmonics);

    // We define the solar radiation pressure, using the default solar flux and accounting only
    // for the eclipsing caused by the Earth.
    let srp_dyn = SolarPressure::default(EARTH_J2000, almanac.clone())?;

    // Finalize setting up the dynamics, specifying the force models (orbital_dyn) separately from the
    // acceleration models (SRP in this case). Use `from_models` to specify multiple accel models.
    let sc_dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn)
        .with_guidance_law(ruggiero_ctrl.clone());

    println!("{:x}", orbit);

    // We specify a minimum step in the propagator because the Ruggiero control would otherwise drive this step very low.
    let (final_state, traj) = Propagator::rk89(
        sc_dynamics.clone(),
        IntegratorOptions::builder()
            .min_step(10.0_f64.seconds())
            .error_ctrl(ErrorControl::RSSCartesianStep)
            .build(),
    )
    .with(sc, almanac.clone())
    .for_duration_with_traj(prop_time)?;

    let fuel_usage = sc.fuel_mass_kg - final_state.fuel_mass_kg;
    println!("{:x}", final_state.orbit);
    println!("fuel usage: {:.3} kg", fuel_usage);

    // Finally, export the results for analysis, including the penumbra percentage throughout the orbit raise.
    traj.to_parquet(
        "./03_geo_raise.parquet",
        Some(vec![
            &EclipseLocator::cislunar(almanac.clone()).to_penumbra_event()
        ]),
        ExportCfg::default(),
        almanac,
    )?;

    for status_line in ruggiero_ctrl.status(&final_state) {
        println!("{status_line}");
    }

    ruggiero_ctrl
        .achieved(&final_state)
        .expect("objective not achieved");

    Ok(())
}

examples/03_geo_analysis/drift.rs (line 39)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();
    // Dynamics models require planetary constants and ephemerides to be defined.
    // Let's start by grabbing those by using ANISE's latest MetaAlmanac.
    // This will automatically download the DE440s planetary ephemeris,
    // the daily-updated Earth Orientation Parameters, the high fidelity Moon orientation
    // parameters (for the Moon Mean Earth and Moon Principal Axes frames), and the PCK11
    // planetary constants kernels.
    // For details, refer to https://github.com/nyx-space/anise/blob/master/data/latest.dhall.
    // Note that we place the Almanac into an Arc so we can clone it cheaply and provide read-only
    // references to many functions.
    let almanac = Arc::new(MetaAlmanac::latest().map_err(Box::new)?);
    // Define the orbit epoch
    let epoch = Epoch::from_gregorian_utc_hms(2024, 2, 29, 12, 13, 14);

    // Define the orbit.
    // First we need to fetch the Earth J2000 from information from the Almanac.
    // This allows the frame to include the gravitational parameters and the shape of the Earth,
    // defined as a tri-axial ellipoid. Note that this shape can be changed manually or in the Almanac
    // by loading a different set of planetary constants.
    let earth_j2000 = almanac.frame_from_uid(EARTH_J2000)?;

    // Placing this GEO bird just above Colorado.
    // In theory, the eccentricity is zero, but in practice, it's about 1e-5 to 1e-6 at best.
    let orbit = Orbit::try_keplerian(42164.0, 1e-5, 0., 163.0, 75.0, 0.0, epoch, earth_j2000)?;
    // Print in in Keplerian form.
    println!("{orbit:x}");

    let state_bf = almanac.transform_to(orbit, IAU_EARTH_FRAME, None)?;
    let (orig_lat_deg, orig_long_deg, orig_alt_km) = state_bf.latlongalt()?;

    // Nyx is used for high fidelity propagation, not Keplerian propagation as above.
    // Nyx only propagates Spacecraft at the moment, which allows it to account for acceleration
    // models such as solar radiation pressure.

    // Let's build a cubesat sized spacecraft, with an SRP area of 10 cm^2 and a mass of 9.6 kg.
    let sc = Spacecraft::builder()
        .orbit(orbit)
        .dry_mass_kg(9.60)
        .srp(SrpConfig {
            area_m2: 10e-4,
            cr: 1.1,
        })
        .build();
    println!("{sc:x}");

    // Set up the spacecraft dynamics.

    // Specify that the orbital dynamics must account for the graviational pull of the Moon and the Sun.
    // The gravity of the Earth will also be accounted for since the spaceraft in an Earth orbit.
    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![MOON, SUN]);

    // We want to include the spherical harmonics, so let's download the gravitational data from the Nyx Cloud.
    // We're using the JGM3 model here, which is the default in GMAT.
    let mut jgm3_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/JGM3.cof.gz".to_string(),
        crc32: Some(0xF446F027), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    // And let's download it if we don't have it yet.
    jgm3_meta.process(true)?;

    // Build the spherical harmonics.
    // The harmonics must be computed in the body fixed frame.
    // We're using the long term prediction of the Earth centered Earth fixed frame, IAU Earth.
    let harmonics_21x21 = Harmonics::from_stor(
        almanac.frame_from_uid(IAU_EARTH_FRAME)?,
        HarmonicsMem::from_cof(&jgm3_meta.uri, 21, 21, true).unwrap(),
    );

    // Include the spherical harmonics into the orbital dynamics.
    orbital_dyn.accel_models.push(harmonics_21x21);

    // We define the solar radiation pressure, using the default solar flux and accounting only
    // for the eclipsing caused by the Earth and Moon.
    let srp_dyn = SolarPressure::new(vec![EARTH_J2000, MOON_J2000], almanac.clone())?;

    // Finalize setting up the dynamics, specifying the force models (orbital_dyn) separately from the
    // acceleration models (SRP in this case). Use `from_models` to specify multiple accel models.
    let dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn);

    println!("{dynamics}");

    // Finally, let's propagate this orbit to the same epoch as above.
    // The first returned value is the spacecraft state at the final epoch.
    // The second value is the full trajectory where the step size is variable step used by the propagator.
    let (future_sc, trajectory) = Propagator::default(dynamics)
        .with(sc, almanac.clone())
        .until_epoch_with_traj(epoch + Unit::Century * 0.03)?;

    println!("=== High fidelity propagation ===");
    println!(
        "SMA changed by {:.3} km",
        orbit.sma_km()? - future_sc.orbit.sma_km()?
    );
    println!(
        "ECC changed by {:.6}",
        orbit.ecc()? - future_sc.orbit.ecc()?
    );
    println!(
        "INC changed by {:.3e} deg",
        orbit.inc_deg()? - future_sc.orbit.inc_deg()?
    );
    println!(
        "RAAN changed by {:.3} deg",
        orbit.raan_deg()? - future_sc.orbit.raan_deg()?
    );
    println!(
        "AOP changed by {:.3} deg",
        orbit.aop_deg()? - future_sc.orbit.aop_deg()?
    );
    println!(
        "TA changed by {:.3} deg",
        orbit.ta_deg()? - future_sc.orbit.ta_deg()?
    );

    // We also have access to the full trajectory throughout the propagation.
    println!("{trajectory}");

    println!("Spacecraft params after 3 years without active control:\n{future_sc:x}");

    // With the trajectory, let's build a few data products.

    // 1. Export the trajectory as a parquet file, which includes the Keplerian orbital elements.

    let analysis_step = Unit::Minute * 5;

    trajectory.to_parquet(
        "./03_geo_hf_prop.parquet",
        Some(vec![
            &EclipseLocator::cislunar(almanac.clone()).to_penumbra_event()
        ]),
        ExportCfg::builder().step(analysis_step).build(),
        almanac.clone(),
    )?;

    // 2. Compute the latitude, longitude, and altitude throughout the trajectory by rotating the spacecraft position into the Earth body fixed frame.

    // We iterate over the trajectory, grabbing a state every two minutes.
    let mut offset_s = vec![];
    let mut epoch_str = vec![];
    let mut longitude_deg = vec![];
    let mut latitude_deg = vec![];
    let mut altitude_km = vec![];

    for state in trajectory.every(analysis_step) {
        // Convert the GEO bird state into the body fixed frame, and keep track of its latitude, longitude, and altitude.
        // These define the GEO stationkeeping box.

        let this_epoch = state.epoch();

        offset_s.push((this_epoch - orbit.epoch).to_seconds());
        epoch_str.push(this_epoch.to_isoformat());

        let state_bf = almanac.transform_to(state.orbit, IAU_EARTH_FRAME, None)?;
        let (lat_deg, long_deg, alt_km) = state_bf.latlongalt()?;
        longitude_deg.push(long_deg);
        latitude_deg.push(lat_deg);
        altitude_km.push(alt_km);
    }

    println!(
        "Longitude changed by {:.3} deg -- Box is 0.1 deg E-W",
        orig_long_deg - longitude_deg.last().unwrap()
    );

    println!(
        "Latitude changed by {:.3} deg -- Box is 0.05 deg N-S",
        orig_lat_deg - latitude_deg.last().unwrap()
    );

    println!(
        "Altitude changed by {:.3} km -- Box is 30 km",
        orig_alt_km - altitude_km.last().unwrap()
    );

    // Build the station keeping data frame.
    let mut sk_df = df!(
        "Offset (s)" => offset_s.clone(),
        "Epoch (UTC)" => epoch_str.clone(),
        "Longitude E-W (deg)" => longitude_deg,
        "Latitude N-S (deg)" => latitude_deg,
        "Altitude (km)" => altitude_km,

    )?;

    // Create a file to write the Parquet to
    let file = File::create("./03_geo_lla.parquet").expect("Could not create file");

    // Create a ParquetWriter and write the DataFrame to the file
    ParquetWriter::new(file).finish(&mut sk_df)?;

    Ok(())
}

examples/01_orbit_prop/main.rs (line 40)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();
    // Dynamics models require planetary constants and ephemerides to be defined.
    // Let's start by grabbing those by using ANISE's latest MetaAlmanac.
    // This will automatically download the DE440s planetary ephemeris,
    // the daily-updated Earth Orientation Parameters, the high fidelity Moon orientation
    // parameters (for the Moon Mean Earth and Moon Principal Axes frames), and the PCK11
    // planetary constants kernels.
    // For details, refer to https://github.com/nyx-space/anise/blob/master/data/latest.dhall.
    // Note that we place the Almanac into an Arc so we can clone it cheaply and provide read-only
    // references to many functions.
    let almanac = Arc::new(MetaAlmanac::latest().map_err(Box::new)?);
    // Define the orbit epoch
    let epoch = Epoch::from_gregorian_utc_hms(2024, 2, 29, 12, 13, 14);

    // Define the orbit.
    // First we need to fetch the Earth J2000 from information from the Almanac.
    // This allows the frame to include the gravitational parameters and the shape of the Earth,
    // defined as a tri-axial ellipoid. Note that this shape can be changed manually or in the Almanac
    // by loading a different set of planetary constants.
    let earth_j2000 = almanac.frame_from_uid(EARTH_J2000)?;

    let orbit =
        Orbit::try_keplerian_altitude(300.0, 0.015, 68.5, 65.2, 75.0, 0.0, epoch, earth_j2000)?;
    // Print in in Keplerian form.
    println!("{orbit:x}");

    // There are two ways to propagate an orbit. We can make a quick approximation assuming only two-body
    // motion. This is a useful first order approximation but it isn't used in real-world applications.

    // This approach is a feature of ANISE.
    let future_orbit_tb = orbit.at_epoch(epoch + Unit::Day * 3)?;
    println!("{future_orbit_tb:x}");

    // Two body propagation relies solely on Kepler's laws, so only the true anomaly will change.
    println!(
        "SMA changed by {:.3e} km",
        orbit.sma_km()? - future_orbit_tb.sma_km()?
    );
    println!(
        "ECC changed by {:.3e}",
        orbit.ecc()? - future_orbit_tb.ecc()?
    );
    println!(
        "INC changed by {:.3e} deg",
        orbit.inc_deg()? - future_orbit_tb.inc_deg()?
    );
    println!(
        "RAAN changed by {:.3e} deg",
        orbit.raan_deg()? - future_orbit_tb.raan_deg()?
    );
    println!(
        "AOP changed by {:.3e} deg",
        orbit.aop_deg()? - future_orbit_tb.aop_deg()?
    );
    println!(
        "TA changed by {:.3} deg",
        orbit.ta_deg()? - future_orbit_tb.ta_deg()?
    );

    // Nyx is used for high fidelity propagation, not Keplerian propagation as above.
    // Nyx only propagates Spacecraft at the moment, which allows it to account for acceleration
    // models such as solar radiation pressure.

    // Let's build a cubesat sized spacecraft, with an SRP area of 10 cm^2 and a mass of 9.6 kg.
    let sc = Spacecraft::builder()
        .orbit(orbit)
        .dry_mass_kg(9.60)
        .srp(SrpConfig {
            area_m2: 10e-4,
            cr: 1.1,
        })
        .build();
    println!("{sc:x}");

    // Set up the spacecraft dynamics.

    // Specify that the orbital dynamics must account for the graviational pull of the Moon and the Sun.
    // The gravity of the Earth will also be accounted for since the spaceraft in an Earth orbit.
    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![MOON, SUN]);

    // We want to include the spherical harmonics, so let's download the gravitational data from the Nyx Cloud.
    // We're using the JGM3 model here, which is the default in GMAT.
    let mut jgm3_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/JGM3.cof.gz".to_string(),
        crc32: Some(0xF446F027), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    // And let's download it if we don't have it yet.
    jgm3_meta.process(true)?;

    // Build the spherical harmonics.
    // The harmonics must be computed in the body fixed frame.
    // We're using the long term prediction of the Earth centered Earth fixed frame, IAU Earth.
    let harmonics_21x21 = Harmonics::from_stor(
        almanac.frame_from_uid(IAU_EARTH_FRAME)?,
        HarmonicsMem::from_cof(&jgm3_meta.uri, 21, 21, true).unwrap(),
    );

    // Include the spherical harmonics into the orbital dynamics.
    orbital_dyn.accel_models.push(harmonics_21x21);

    // We define the solar radiation pressure, using the default solar flux and accounting only
    // for the eclipsing caused by the Earth.
    let srp_dyn = SolarPressure::default(EARTH_J2000, almanac.clone())?;

    // Finalize setting up the dynamics, specifying the force models (orbital_dyn) separately from the
    // acceleration models (SRP in this case). Use `from_models` to specify multiple accel models.
    let dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn);

    println!("{dynamics}");

    // Finally, let's propagate this orbit to the same epoch as above.
    // The first returned value is the spacecraft state at the final epoch.
    // The second value is the full trajectory where the step size is variable step used by the propagator.
    let (future_sc, trajectory) = Propagator::default(dynamics)
        .with(sc, almanac.clone())
        .until_epoch_with_traj(future_orbit_tb.epoch)?;

    println!("=== High fidelity propagation ===");
    println!(
        "SMA changed by {:.3} km",
        orbit.sma_km()? - future_sc.orbit.sma_km()?
    );
    println!(
        "ECC changed by {:.6}",
        orbit.ecc()? - future_sc.orbit.ecc()?
    );
    println!(
        "INC changed by {:.3e} deg",
        orbit.inc_deg()? - future_sc.orbit.inc_deg()?
    );
    println!(
        "RAAN changed by {:.3} deg",
        orbit.raan_deg()? - future_sc.orbit.raan_deg()?
    );
    println!(
        "AOP changed by {:.3} deg",
        orbit.aop_deg()? - future_sc.orbit.aop_deg()?
    );
    println!(
        "TA changed by {:.3} deg",
        orbit.ta_deg()? - future_sc.orbit.ta_deg()?
    );

    // We also have access to the full trajectory throughout the propagation.
    println!("{trajectory}");

    // With the trajectory, let's build a few data products.

    // 1. Export the trajectory as a CCSDS OEM version 2.0 file and as a parquet file, which includes the Keplerian orbital elements.

    trajectory.to_oem_file(
        "./01_cubesat_hf_prop.oem",
        ExportCfg::builder().step(Unit::Minute * 2).build(),
    )?;

    trajectory.to_parquet_with_cfg(
        "./01_cubesat_hf_prop.parquet",
        ExportCfg::builder().step(Unit::Minute * 2).build(),
        almanac.clone(),
    )?;

    // 2. Compare the difference in the radial-intrack-crosstrack frame between the high fidelity
    // and Keplerian propagation. The RIC frame is commonly used to compute the difference in position
    // and velocity of different spacecraft.
    // 3. Compute the azimuth, elevation, range, and range-rate data of that spacecraft as seen from Boulder, CO, USA.

    let boulder_station = GroundStation::from_point(
        "Boulder, CO, USA".to_string(),
        40.014984,   // latitude in degrees
        -105.270546, // longitude in degrees
        1.6550,      // altitude in kilometers
        almanac.frame_from_uid(IAU_EARTH_FRAME)?,
    );

    // We iterate over the trajectory, grabbing a state every two minutes.
    let mut offset_s = vec![];
    let mut epoch_str = vec![];
    let mut ric_x_km = vec![];
    let mut ric_y_km = vec![];
    let mut ric_z_km = vec![];
    let mut ric_vx_km_s = vec![];
    let mut ric_vy_km_s = vec![];
    let mut ric_vz_km_s = vec![];

    let mut azimuth_deg = vec![];
    let mut elevation_deg = vec![];
    let mut range_km = vec![];
    let mut range_rate_km_s = vec![];
    for state in trajectory.every(Unit::Minute * 2) {
        // Try to compute the Keplerian/two body state just in time.
        // This method occasionally fails to converge on an appropriate true anomaly
        // from the mean anomaly. If that happens, we just skip this state.
        // The high fidelity and Keplerian states diverge continuously, and we're curious
        // about the divergence in this quick analysis.
        let this_epoch = state.epoch();
        match orbit.at_epoch(this_epoch) {
            Ok(tb_then) => {
                offset_s.push((this_epoch - orbit.epoch).to_seconds());
                epoch_str.push(format!("{this_epoch}"));
                // Compute the two body state just in time.
                let ric = state.orbit.ric_difference(&tb_then)?;
                ric_x_km.push(ric.radius_km.x);
                ric_y_km.push(ric.radius_km.y);
                ric_z_km.push(ric.radius_km.z);
                ric_vx_km_s.push(ric.velocity_km_s.x);
                ric_vy_km_s.push(ric.velocity_km_s.y);
                ric_vz_km_s.push(ric.velocity_km_s.z);

                // Compute the AER data for each state.
                let aer = almanac.azimuth_elevation_range_sez(
                    state.orbit,
                    boulder_station.to_orbit(this_epoch, &almanac)?,
                    None,
                    None,
                )?;
                azimuth_deg.push(aer.azimuth_deg);
                elevation_deg.push(aer.elevation_deg);
                range_km.push(aer.range_km);
                range_rate_km_s.push(aer.range_rate_km_s);
            }
            Err(e) => warn!("{} {e}", state.epoch()),
        };
    }

    // Build the data frames.
    let ric_df = df!(
        "Offset (s)" => offset_s.clone(),
        "Epoch" => epoch_str.clone(),
        "RIC X (km)" => ric_x_km,
        "RIC Y (km)" => ric_y_km,
        "RIC Z (km)" => ric_z_km,
        "RIC VX (km/s)" => ric_vx_km_s,
        "RIC VY (km/s)" => ric_vy_km_s,
        "RIC VZ (km/s)" => ric_vz_km_s,
    )?;

    println!("RIC difference at start\n{}", ric_df.head(Some(10)));
    println!("RIC difference at end\n{}", ric_df.tail(Some(10)));

    let aer_df = df!(
        "Offset (s)" => offset_s.clone(),
        "Epoch" => epoch_str.clone(),
        "azimuth (deg)" => azimuth_deg,
        "elevation (deg)" => elevation_deg,
        "range (km)" => range_km,
        "range rate (km/s)" => range_rate_km_s,
    )?;

    // Finally, let's see when the spacecraft is visible, assuming 15 degrees minimum elevation.
    let mask = aer_df.column("elevation (deg)")?.gt(15.0)?;
    let cubesat_visible = aer_df.filter(&mask)?;

    println!("{cubesat_visible}");

    Ok(())
}

pub fn from_gregorian( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, nanos: u32, time_scale: TimeScale, ) -> Epoch

Builds an Epoch from the provided Gregorian date and time in the provided time scale. If invalid date is provided, this function will panic. Use maybe_from_gregorian if unsure.

pub fn from_gregorian_at_midnight( year: i32, month: u8, day: u8, time_scale: TimeScale, ) -> Epoch

Initialize from Gregorian date in UTC at midnight

pub fn from_gregorian_at_noon( year: i32, month: u8, day: u8, time_scale: TimeScale, ) -> Epoch

Initialize from Gregorian date in UTC at noon

pub fn from_gregorian_hms( year: i32, month: u8, day: u8, hour: u8, minute: u8, second: u8, time_scale: TimeScale, ) -> Epoch

Initialize from the Gregorian date and time (without the nanoseconds) in UTC

pub fn from_gregorian_str(s_in: &str) -> Result<Epoch, HifitimeError>

Converts a Gregorian date time in ISO8601 or RFC3339 format into an Epoch, accounting for the time zone designator and the time scale.

Definition

1. Time Zone Designator: this is either a Z (lower or upper case) to specify UTC, or an offset in hours and minutes off of UTC, such as +01:00 for UTC plus one hour and zero minutes.
2. Time system (or time “scale”): UTC, TT, TAI, TDB, ET, etc.

Converts an ISO8601 or RFC3339 datetime representation to an Epoch. If no time scale is specified, then UTC is assumed. A time scale may be specified in addition to the format unless The T which separates the date from the time can be replaced with a single whitespace character (\W). The offset is also optional, cf. the examples below.

Example

use hifitime::Epoch;
let dt = Epoch::from_gregorian_utc(2017, 1, 14, 0, 31, 55, 0);
assert_eq!(
    dt,
    Epoch::from_gregorian_str("2017-01-14T00:31:55 UTC").unwrap()
);
assert_eq!(
    dt,
    Epoch::from_gregorian_str("2017-01-14T00:31:55.0000 UTC").unwrap()
);
assert_eq!(
    dt,
    Epoch::from_gregorian_str("2017-01-14T00:31:55").unwrap()
);
assert_eq!(
    dt,
    Epoch::from_gregorian_str("2017-01-14 00:31:55").unwrap()
);
// Regression test for #90
assert_eq!(
    Epoch::from_gregorian_utc(2017, 1, 14, 0, 31, 55, 811000000),
    Epoch::from_gregorian_str("2017-01-14 00:31:55.811 UTC").unwrap()
);
assert_eq!(
    Epoch::from_gregorian_utc(2017, 1, 14, 0, 31, 55, 811200000),
    Epoch::from_gregorian_str("2017-01-14 00:31:55.8112 UTC").unwrap()
);
// Example from https://www.w3.org/TR/NOTE-datetime
assert_eq!(
    Epoch::from_gregorian_utc_hms(1994, 11, 5, 13, 15, 30),
    Epoch::from_gregorian_str("1994-11-05T13:15:30Z").unwrap()
);
assert_eq!(
    Epoch::from_gregorian_utc_hms(1994, 11, 5, 13, 15, 30),
    Epoch::from_gregorian_str("1994-11-05T08:15:30-05:00").unwrap()
);

impl Epoch

pub const fn from_tai_duration(duration: Duration) -> Epoch

Creates a new Epoch from a Duration as the time difference between this epoch and TAI reference epoch.

pub fn to_duration_since_j1900(&self) -> Duration

pub fn from_tai_parts(centuries: i16, nanoseconds: u64) -> Epoch

Creates a new Epoch from its centuries and nanosecond since the TAI reference epoch.

pub fn from_tai_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the provided TAI seconds since 1900 January 01 at midnight

pub fn from_tai_days(days: f64) -> Epoch

Initialize an Epoch from the provided TAI days since 1900 January 01 at midnight

pub fn from_utc_duration(duration: Duration) -> Epoch

Initialize an Epoch from the provided UTC seconds since 1900 January 01 at midnight

pub fn from_utc_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the provided UTC seconds since 1900 January 01 at midnight

pub fn from_utc_days(days: f64) -> Epoch

Initialize an Epoch from the provided UTC days since 1900 January 01 at midnight

pub fn from_gpst_duration(duration: Duration) -> Epoch

Initialize an Epoch from the provided duration since 1980 January 6 at midnight

pub fn from_qzsst_duration(duration: Duration) -> Epoch

Initialize an Epoch from the provided duration since 1980 January 6 at midnight

pub fn from_gst_duration(duration: Duration) -> Epoch

Initialize an Epoch from the provided duration since August 21st 1999 midnight

pub fn from_bdt_duration(duration: Duration) -> Epoch

Initialize an Epoch from the provided duration since January 1st midnight

pub fn from_mjd_tai(days: f64) -> Epoch

pub fn from_mjd_in_time_scale(days: f64, time_scale: TimeScale) -> Epoch

pub fn from_mjd_utc(days: f64) -> Epoch

pub fn from_mjd_gpst(days: f64) -> Epoch

pub fn from_mjd_qzsst(days: f64) -> Epoch

pub fn from_mjd_gst(days: f64) -> Epoch

pub fn from_mjd_bdt(days: f64) -> Epoch

pub fn from_jde_tai(days: f64) -> Epoch

pub fn from_jde_in_time_scale(days: f64, time_scale: TimeScale) -> Epoch

pub fn from_jde_utc(days: f64) -> Epoch

pub fn from_jde_gpst(days: f64) -> Epoch

pub fn from_jde_qzsst(days: f64) -> Epoch

pub fn from_jde_gst(days: f64) -> Epoch

pub fn from_jde_bdt(days: f64) -> Epoch

pub fn from_tt_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the provided TT seconds (approximated to 32.184s delta from TAI)

pub fn from_tt_duration(duration: Duration) -> Epoch

Initialize an Epoch from the provided TT seconds (approximated to 32.184s delta from TAI)

pub fn from_et_seconds(seconds_since_j2000: f64) -> Epoch

Initialize an Epoch from the Ephemeris Time seconds past 2000 JAN 01 (J2000 reference)

pub fn from_et_duration(duration_since_j2000: Duration) -> Epoch

Initializes an Epoch from the duration between J2000 and the current epoch as per NAIF SPICE.

Limitation

This method uses a Newton Raphson iteration to find the appropriate TAI duration. This method is only accuracy to a few nanoseconds. Hence, when calling as_et_duration() and re-initializing it with from_et_duration you may have a few nanoseconds of difference (expect less than 10 ns).

Warning

The et2utc function of NAIF SPICE will assume that there are 9 leap seconds before 01 JAN 1972, as this date introduces 10 leap seconds. At the time of writing, this does not seem to be in line with IERS and the documentation in the leap seconds list.

In order to match SPICE, the as_et_duration() function will manually get rid of that difference.

pub fn from_tdb_seconds(seconds_j2000: f64) -> Epoch

Initialize an Epoch from Dynamic Barycentric Time (TDB) seconds past 2000 JAN 01 midnight (difference than SPICE) NOTE: This uses the ESA algorithm, which is a notch more complicated than the SPICE algorithm, but more precise. In fact, SPICE algorithm is precise +/- 30 microseconds for a century whereas ESA algorithm should be exactly correct.

pub fn from_tdb_duration(duration_since_j2000: Duration) -> Epoch

Initialize from Dynamic Barycentric Time (TDB) (same as SPICE ephemeris time) whose epoch is 2000 JAN 01 noon TAI.

pub fn from_jde_et(days: f64) -> Epoch

Initialize from the JDE days

pub fn from_jde_tdb(days: f64) -> Epoch

Initialize from Dynamic Barycentric Time (TDB) (same as SPICE ephemeris time) in JD days

pub fn from_gpst_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the number of seconds since the GPS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29).

pub fn from_gpst_days(days: f64) -> Epoch

Initialize an Epoch from the number of days since the GPS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29).

pub fn from_gpst_nanoseconds(nanoseconds: u64) -> Epoch

Initialize an Epoch from the number of nanoseconds since the GPS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). This may be useful for time keeping devices that use GPS as a time source.

pub fn from_qzsst_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the number of seconds since the QZSS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29).

pub fn from_qzsst_days(days: f64) -> Epoch

Initialize an Epoch from the number of days since the QZSS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29).

pub fn from_qzsst_nanoseconds(nanoseconds: u64) -> Epoch

Initialize an Epoch from the number of nanoseconds since the QZSS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). This may be useful for time keeping devices that use QZSS as a time source.

pub fn from_gst_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the number of seconds since the GST Time Epoch, starting August 21st 1999 midnight (UTC) (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS).

pub fn from_gst_days(days: f64) -> Epoch

Initialize an Epoch from the number of days since the GST Time Epoch, starting August 21st 1999 midnight (UTC) (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS)

pub fn from_gst_nanoseconds(nanoseconds: u64) -> Epoch

Initialize an Epoch from the number of nanoseconds since the GPS Time Epoch, starting August 21st 1999 midnight (UTC) (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS)

pub fn from_bdt_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the number of seconds since the BDT Time Epoch, starting on January 1st 2006 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS)

pub fn from_bdt_days(days: f64) -> Epoch

Initialize an Epoch from the number of days since the BDT Time Epoch, starting on January 1st 2006 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS)

pub fn from_bdt_nanoseconds(nanoseconds: u64) -> Epoch

Initialize an Epoch from the number of nanoseconds since the BDT Time Epoch, starting on January 1st 2006 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS). This may be useful for time keeping devices that use BDT as a time source.

pub fn from_unix_duration(duration: Duration) -> Epoch

Initialize an Epoch from the provided duration since UTC midnight 1970 January 01.

pub fn from_unix_seconds(seconds: f64) -> Epoch

Initialize an Epoch from the provided UNIX second timestamp since UTC midnight 1970 January 01.

pub fn from_unix_milliseconds(millisecond: f64) -> Epoch

Initialize an Epoch from the provided UNIX millisecond timestamp since UTC midnight 1970 January 01.

pub fn from_str_with_format( s_in: &str, format: Format, ) -> Result<Epoch, HifitimeError>

Initializes an Epoch from the provided Format.

pub fn from_format_str( s_in: &str, format_str: &str, ) -> Result<Epoch, HifitimeError>

Initializes an Epoch from the Format as a string.

pub fn from_time_of_week( week: u32, nanoseconds: u64, time_scale: TimeScale, ) -> Epoch

Builds an Epoch from given week: elapsed weeks counter into the desired Time scale, and the amount of nanoseconds within that week. For example, this is how GPS vehicles describe a GPST epoch.

Note that this constructor relies on 128 bit integer math and may be slow on embedded devices.

pub fn from_time_of_week_utc(week: u32, nanoseconds: u64) -> Epoch

Builds a UTC Epoch from given week: elapsed weeks counter and “ns” amount of nanoseconds since closest Sunday Midnight.

pub fn from_day_of_year(year: i32, days: f64, time_scale: TimeScale) -> Epoch

Builds an Epoch from the provided year, days in the year, and a time scale.

Limitations

In the TDB or ET time scales, there may be an error of up to 750 nanoseconds when initializing an Epoch this way. This is because we first initialize the epoch in Gregorian scale and then apply the TDB/ET offset, but that offset actually depends on the precise time.

Day couting behavior

The day counter starts at 01, in other words, 01 January is day 1 of the counter, as per the GPS specificiations.

impl Epoch

pub fn min(&self, other: Epoch) -> Epoch

Returns the minimum of the two epochs.

use hifitime::Epoch;

let e0 = Epoch::from_gregorian_utc_at_midnight(2022, 10, 20);
let e1 = Epoch::from_gregorian_utc_at_midnight(2022, 10, 21);

assert_eq!(e0, e1.min(e0));
assert_eq!(e0, e0.min(e1));

Note: this uses a pointer to self which will be copied immediately because Python requires a pointer.

pub fn max(&self, other: Epoch) -> Epoch

Returns the maximum of the two epochs.

use hifitime::Epoch;

let e0 = Epoch::from_gregorian_utc_at_midnight(2022, 10, 20);
let e1 = Epoch::from_gregorian_utc_at_midnight(2022, 10, 21);

assert_eq!(e1, e1.max(e0));
assert_eq!(e1, e0.max(e1));

Note: this uses a pointer to self which will be copied immediately because Python requires a pointer.

pub fn floor(&self, duration: Duration) -> Epoch

Floors this epoch to the closest provided duration

Example

use hifitime::{Epoch, TimeUnits};

let e = Epoch::from_gregorian_tai_hms(2022, 5, 20, 17, 57, 43);
assert_eq!(
    e.floor(1.hours()),
    Epoch::from_gregorian_tai_hms(2022, 5, 20, 17, 0, 0)
);

let e = Epoch::from_gregorian_tai(2022, 10, 3, 17, 44, 29, 898032665);
assert_eq!(
    e.floor(3.minutes()),
    Epoch::from_gregorian_tai_hms(2022, 10, 3, 17, 42, 0)
);

pub fn ceil(&self, duration: Duration) -> Epoch

Ceils this epoch to the closest provided duration in the TAI time scale

Example

use hifitime::{Epoch, TimeUnits};

let e = Epoch::from_gregorian_tai_hms(2022, 5, 20, 17, 57, 43);
assert_eq!(
    e.ceil(1.hours()),
    Epoch::from_gregorian_tai_hms(2022, 5, 20, 18, 0, 0)
);

// 45 minutes is a multiple of 3 minutes, hence this result
let e = Epoch::from_gregorian_tai(2022, 10, 3, 17, 44, 29, 898032665);
assert_eq!(
    e.ceil(3.minutes()),
    Epoch::from_gregorian_tai_hms(2022, 10, 3, 17, 45, 0)
);

pub fn round(&self, duration: Duration) -> Epoch

Rounds this epoch to the closest provided duration in TAI

Example

use hifitime::{Epoch, TimeUnits};

let e = Epoch::from_gregorian_tai_hms(2022, 5, 20, 17, 57, 43);
assert_eq!(
    e.round(1.hours()),
    Epoch::from_gregorian_tai_hms(2022, 5, 20, 18, 0, 0)
);

pub fn to_time_of_week(&self) -> (u32, u64)

Converts this epoch into the time of week, represented as a rolling week counter into that time scale and the number of nanoseconds elapsed in current week (since closest Sunday midnight). This is usually how GNSS receivers describe a timestamp.

pub fn weekday_in_time_scale(&self, time_scale: TimeScale) -> Weekday

Returns the weekday in provided time scale ASSUMING that the reference epoch of that time scale is a Monday. You probably do not want to use this. You probably either want weekday() or weekday_utc(). Several time scales do not have a reference day that’s on a Monday, e.g. BDT.

pub fn weekday(&self) -> Weekday

Returns weekday (uses the TAI representation for this calculation).

pub fn weekday_utc(&self) -> Weekday

Returns weekday in UTC timescale

pub fn next(&self, weekday: Weekday) -> Epoch

Returns the next weekday.

use hifitime::prelude::*;

let epoch = Epoch::from_gregorian_utc_at_midnight(1988, 1, 2);
assert_eq!(epoch.weekday_utc(), Weekday::Saturday);
assert_eq!(epoch.next(Weekday::Sunday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 3));
assert_eq!(epoch.next(Weekday::Monday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 4));
assert_eq!(epoch.next(Weekday::Tuesday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 5));
assert_eq!(epoch.next(Weekday::Wednesday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 6));
assert_eq!(epoch.next(Weekday::Thursday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 7));
assert_eq!(epoch.next(Weekday::Friday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 8));
assert_eq!(epoch.next(Weekday::Saturday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 9));

pub fn next_weekday_at_midnight(&self, weekday: Weekday) -> Epoch

pub fn next_weekday_at_noon(&self, weekday: Weekday) -> Epoch

pub fn previous(&self, weekday: Weekday) -> Epoch

Returns the next weekday.

use hifitime::prelude::*;

let epoch = Epoch::from_gregorian_utc_at_midnight(1988, 1, 2);
assert_eq!(epoch.previous(Weekday::Friday), Epoch::from_gregorian_utc_at_midnight(1988, 1, 1));
assert_eq!(epoch.previous(Weekday::Thursday), Epoch::from_gregorian_utc_at_midnight(1987, 12, 31));
assert_eq!(epoch.previous(Weekday::Wednesday), Epoch::from_gregorian_utc_at_midnight(1987, 12, 30));
assert_eq!(epoch.previous(Weekday::Tuesday), Epoch::from_gregorian_utc_at_midnight(1987, 12, 29));
assert_eq!(epoch.previous(Weekday::Monday), Epoch::from_gregorian_utc_at_midnight(1987, 12, 28));
assert_eq!(epoch.previous(Weekday::Sunday), Epoch::from_gregorian_utc_at_midnight(1987, 12, 27));
assert_eq!(epoch.previous(Weekday::Saturday), Epoch::from_gregorian_utc_at_midnight(1987, 12, 26));

pub fn previous_weekday_at_midnight(&self, weekday: Weekday) -> Epoch

pub fn previous_weekday_at_noon(&self, weekday: Weekday) -> Epoch

impl Epoch

pub fn with_hms(&self, hours: u64, minutes: u64, seconds: u64) -> Epoch

Returns a copy of self where the time is set to the provided hours, minutes, seconds Invalid number of hours, minutes, and seconds will overflow into their higher unit. Warning: this does not set the subdivisions of second to zero.

pub fn with_hms_from(&self, other: Epoch) -> Epoch

Returns a copy of self where the hours, minutes, seconds is set to the time of the provided epoch but the sub-second parts are kept from the current epoch.

use hifitime::prelude::*;

let epoch = Epoch::from_gregorian_utc(2022, 12, 01, 10, 11, 12, 13);
let other_utc = Epoch::from_gregorian_utc(2024, 12, 01, 20, 21, 22, 23);
let other = other_utc.to_time_scale(TimeScale::TDB);

assert_eq!(
    epoch.with_hms_from(other),
    Epoch::from_gregorian_utc(2022, 12, 01, 20, 21, 22, 13)
);

pub fn with_time_from(&self, other: Epoch) -> Epoch

Returns a copy of self where all of the time components (hours, minutes, seconds, and sub-seconds) are set to the time of the provided epoch.

use hifitime::prelude::*;

let epoch = Epoch::from_gregorian_utc(2022, 12, 01, 10, 11, 12, 13);
let other_utc = Epoch::from_gregorian_utc(2024, 12, 01, 20, 21, 22, 23);
// If the other Epoch is in another time scale, it does not matter, it will be converted to the correct time scale.
let other = other_utc.to_time_scale(TimeScale::TDB);

assert_eq!(
    epoch.with_time_from(other),
    Epoch::from_gregorian_utc(2022, 12, 01, 20, 21, 22, 23)
);

pub fn with_hms_strict(&self, hours: u64, minutes: u64, seconds: u64) -> Epoch

Returns a copy of self where the time is set to the provided hours, minutes, seconds Invalid number of hours, minutes, and seconds will overflow into their higher unit. Warning: this will set the subdivisions of seconds to zero.

pub fn with_hms_strict_from(&self, other: Epoch) -> Epoch

Returns a copy of self where the time is set to the time of the other epoch but the subseconds are set to zero.

use hifitime::prelude::*;

let epoch = Epoch::from_gregorian_utc(2022, 12, 01, 10, 11, 12, 13);
let other_utc = Epoch::from_gregorian_utc(2024, 12, 01, 20, 21, 22, 23);
let other = other_utc.to_time_scale(TimeScale::TDB);

assert_eq!(
    epoch.with_hms_strict_from(other),
    Epoch::from_gregorian_utc(2022, 12, 01, 20, 21, 22, 0)
);

impl Epoch

pub fn now() -> Result<Epoch, HifitimeError>

Initializes a new Epoch from now. WARNING: This assumes that the system time returns the time in UTC (which is the case on Linux) Uses std::time::SystemTime::now or javascript interop under the hood

impl Epoch

pub fn leap_seconds_with<L>(&self, iers_only: bool, provider: L) -> Option<f64>

where L: LeapSecondProvider,

Get the accumulated number of leap seconds up to this Epoch from the provided LeapSecondProvider. Returns None if the epoch is before 1960, year at which UTC was defined.

Why does this function return an Option when the other returns a value

This is to match the iauDat function of SOFA (src/dat.c). That function will return a warning and give up if the start date is before 1960.

pub const fn from_duration(duration: Duration, ts: TimeScale) -> Epoch

Creates an epoch from given duration expressed in given timescale, i.e. since the given time scale’s reference epoch.

For example, if the duration is 1 day and the time scale is Ephemeris Time, then this will create an epoch of 2000-01-02 at midnight ET. If the duration is 1 day and the time scale is TAI, this will create an epoch of 1900-01-02 at noon, because the TAI reference epoch in Hifitime is chosen to be the J1900 epoch. In case of ET, TDB Timescales, a duration since J2000 is expected.

impl Epoch

pub fn to_time_scale(&self, ts: TimeScale) -> Epoch

Converts self to another time scale

As per the Rust naming convention, this borrows an Epoch and returns an owned Epoch.

:type ts: TimeScale :rtype: Epoch

pub fn leap_seconds_iers(&self) -> i32

Get the accumulated number of leap seconds up to this Epoch accounting only for the IERS leap seconds. :rtype: int

pub fn leap_seconds(&self, iers_only: bool) -> Option<f64>

Get the accumulated number of leap seconds up to this Epoch accounting only for the IERS leap seconds and the SOFA scaling from 1960 to 1972, depending on flag. Returns None if the epoch is before 1960, year at which UTC was defined.

Why does this function return an Option when the other returns a value

This is to match the iauDat function of SOFA (src/dat.c). That function will return a warning and give up if the start date is before 1960. :type iers_only: bool :rtype: float

pub fn to_isoformat(&self) -> String

The standard ISO format of this epoch (six digits of subseconds) in the current time scale, refer to https://docs.rs/hifitime/latest/hifitime/efmt/format/struct.Format.html for format options. :rtype: str

Examples found in repository

examples/03_geo_analysis/drift.rs (line 177)

fn main() -> Result<(), Box<dyn Error>> {
    pel::init();
    // Dynamics models require planetary constants and ephemerides to be defined.
    // Let's start by grabbing those by using ANISE's latest MetaAlmanac.
    // This will automatically download the DE440s planetary ephemeris,
    // the daily-updated Earth Orientation Parameters, the high fidelity Moon orientation
    // parameters (for the Moon Mean Earth and Moon Principal Axes frames), and the PCK11
    // planetary constants kernels.
    // For details, refer to https://github.com/nyx-space/anise/blob/master/data/latest.dhall.
    // Note that we place the Almanac into an Arc so we can clone it cheaply and provide read-only
    // references to many functions.
    let almanac = Arc::new(MetaAlmanac::latest().map_err(Box::new)?);
    // Define the orbit epoch
    let epoch = Epoch::from_gregorian_utc_hms(2024, 2, 29, 12, 13, 14);

    // Define the orbit.
    // First we need to fetch the Earth J2000 from information from the Almanac.
    // This allows the frame to include the gravitational parameters and the shape of the Earth,
    // defined as a tri-axial ellipoid. Note that this shape can be changed manually or in the Almanac
    // by loading a different set of planetary constants.
    let earth_j2000 = almanac.frame_from_uid(EARTH_J2000)?;

    // Placing this GEO bird just above Colorado.
    // In theory, the eccentricity is zero, but in practice, it's about 1e-5 to 1e-6 at best.
    let orbit = Orbit::try_keplerian(42164.0, 1e-5, 0., 163.0, 75.0, 0.0, epoch, earth_j2000)?;
    // Print in in Keplerian form.
    println!("{orbit:x}");

    let state_bf = almanac.transform_to(orbit, IAU_EARTH_FRAME, None)?;
    let (orig_lat_deg, orig_long_deg, orig_alt_km) = state_bf.latlongalt()?;

    // Nyx is used for high fidelity propagation, not Keplerian propagation as above.
    // Nyx only propagates Spacecraft at the moment, which allows it to account for acceleration
    // models such as solar radiation pressure.

    // Let's build a cubesat sized spacecraft, with an SRP area of 10 cm^2 and a mass of 9.6 kg.
    let sc = Spacecraft::builder()
        .orbit(orbit)
        .dry_mass_kg(9.60)
        .srp(SrpConfig {
            area_m2: 10e-4,
            cr: 1.1,
        })
        .build();
    println!("{sc:x}");

    // Set up the spacecraft dynamics.

    // Specify that the orbital dynamics must account for the graviational pull of the Moon and the Sun.
    // The gravity of the Earth will also be accounted for since the spaceraft in an Earth orbit.
    let mut orbital_dyn = OrbitalDynamics::point_masses(vec![MOON, SUN]);

    // We want to include the spherical harmonics, so let's download the gravitational data from the Nyx Cloud.
    // We're using the JGM3 model here, which is the default in GMAT.
    let mut jgm3_meta = MetaFile {
        uri: "http://public-data.nyxspace.com/nyx/models/JGM3.cof.gz".to_string(),
        crc32: Some(0xF446F027), // Specifying the CRC32 avoids redownloading it if it's cached.
    };
    // And let's download it if we don't have it yet.
    jgm3_meta.process(true)?;

    // Build the spherical harmonics.
    // The harmonics must be computed in the body fixed frame.
    // We're using the long term prediction of the Earth centered Earth fixed frame, IAU Earth.
    let harmonics_21x21 = Harmonics::from_stor(
        almanac.frame_from_uid(IAU_EARTH_FRAME)?,
        HarmonicsMem::from_cof(&jgm3_meta.uri, 21, 21, true).unwrap(),
    );

    // Include the spherical harmonics into the orbital dynamics.
    orbital_dyn.accel_models.push(harmonics_21x21);

    // We define the solar radiation pressure, using the default solar flux and accounting only
    // for the eclipsing caused by the Earth and Moon.
    let srp_dyn = SolarPressure::new(vec![EARTH_J2000, MOON_J2000], almanac.clone())?;

    // Finalize setting up the dynamics, specifying the force models (orbital_dyn) separately from the
    // acceleration models (SRP in this case). Use `from_models` to specify multiple accel models.
    let dynamics = SpacecraftDynamics::from_model(orbital_dyn, srp_dyn);

    println!("{dynamics}");

    // Finally, let's propagate this orbit to the same epoch as above.
    // The first returned value is the spacecraft state at the final epoch.
    // The second value is the full trajectory where the step size is variable step used by the propagator.
    let (future_sc, trajectory) = Propagator::default(dynamics)
        .with(sc, almanac.clone())
        .until_epoch_with_traj(epoch + Unit::Century * 0.03)?;

    println!("=== High fidelity propagation ===");
    println!(
        "SMA changed by {:.3} km",
        orbit.sma_km()? - future_sc.orbit.sma_km()?
    );
    println!(
        "ECC changed by {:.6}",
        orbit.ecc()? - future_sc.orbit.ecc()?
    );
    println!(
        "INC changed by {:.3e} deg",
        orbit.inc_deg()? - future_sc.orbit.inc_deg()?
    );
    println!(
        "RAAN changed by {:.3} deg",
        orbit.raan_deg()? - future_sc.orbit.raan_deg()?
    );
    println!(
        "AOP changed by {:.3} deg",
        orbit.aop_deg()? - future_sc.orbit.aop_deg()?
    );
    println!(
        "TA changed by {:.3} deg",
        orbit.ta_deg()? - future_sc.orbit.ta_deg()?
    );

    // We also have access to the full trajectory throughout the propagation.
    println!("{trajectory}");

    println!("Spacecraft params after 3 years without active control:\n{future_sc:x}");

    // With the trajectory, let's build a few data products.

    // 1. Export the trajectory as a parquet file, which includes the Keplerian orbital elements.

    let analysis_step = Unit::Minute * 5;

    trajectory.to_parquet(
        "./03_geo_hf_prop.parquet",
        Some(vec![
            &EclipseLocator::cislunar(almanac.clone()).to_penumbra_event()
        ]),
        ExportCfg::builder().step(analysis_step).build(),
        almanac.clone(),
    )?;

    // 2. Compute the latitude, longitude, and altitude throughout the trajectory by rotating the spacecraft position into the Earth body fixed frame.

    // We iterate over the trajectory, grabbing a state every two minutes.
    let mut offset_s = vec![];
    let mut epoch_str = vec![];
    let mut longitude_deg = vec![];
    let mut latitude_deg = vec![];
    let mut altitude_km = vec![];

    for state in trajectory.every(analysis_step) {
        // Convert the GEO bird state into the body fixed frame, and keep track of its latitude, longitude, and altitude.
        // These define the GEO stationkeeping box.

        let this_epoch = state.epoch();

        offset_s.push((this_epoch - orbit.epoch).to_seconds());
        epoch_str.push(this_epoch.to_isoformat());

        let state_bf = almanac.transform_to(state.orbit, IAU_EARTH_FRAME, None)?;
        let (lat_deg, long_deg, alt_km) = state_bf.latlongalt()?;
        longitude_deg.push(long_deg);
        latitude_deg.push(lat_deg);
        altitude_km.push(alt_km);
    }

    println!(
        "Longitude changed by {:.3} deg -- Box is 0.1 deg E-W",
        orig_long_deg - longitude_deg.last().unwrap()
    );

    println!(
        "Latitude changed by {:.3} deg -- Box is 0.05 deg N-S",
        orig_lat_deg - latitude_deg.last().unwrap()
    );

    println!(
        "Altitude changed by {:.3} km -- Box is 30 km",
        orig_alt_km - altitude_km.last().unwrap()
    );

    // Build the station keeping data frame.
    let mut sk_df = df!(
        "Offset (s)" => offset_s.clone(),
        "Epoch (UTC)" => epoch_str.clone(),
        "Longitude E-W (deg)" => longitude_deg,
        "Latitude N-S (deg)" => latitude_deg,
        "Altitude (km)" => altitude_km,

    )?;

    // Create a file to write the Parquet to
    let file = File::create("./03_geo_lla.parquet").expect("Could not create file");

    // Create a ParquetWriter and write the DataFrame to the file
    ParquetWriter::new(file).finish(&mut sk_df)?;

    Ok(())
}

pub fn to_duration_in_time_scale(&self, ts: TimeScale) -> Duration

Returns this epoch with respect to the provided time scale. This is needed to correctly perform duration conversions in dynamical time scales (e.g. TDB). :type ts: TimeScale :rtype: Duration

pub fn to_tai_seconds(&self) -> f64

Returns the number of TAI seconds since J1900 :rtype: float

pub fn to_tai_duration(&self) -> Duration

Returns this time in a Duration past J1900 counted in TAI :rtype: Duration

pub fn to_tai(&self, unit: Unit) -> f64

Returns the epoch as a floating point value in the provided unit :type unit: Unit :rtype: float

pub fn to_tai_parts(&self) -> (i16, u64)

Returns the TAI parts of this duration :rtype: typing.Tuple

pub fn to_tai_days(&self) -> f64

Returns the number of days since J1900 in TAI :rtype: float

pub fn to_utc_seconds(&self) -> f64

Returns the number of UTC seconds since the TAI epoch :rtype: float

pub fn to_utc_duration(&self) -> Duration

Returns this time in a Duration past J1900 counted in UTC :rtype: Duration

pub fn to_utc(&self, unit: Unit) -> f64

Returns the number of UTC seconds since the TAI epoch :type unit: Unit :rtype: float

pub fn to_utc_days(&self) -> f64

Returns the number of UTC days since the TAI epoch :rtype: float

pub fn to_mjd_tai_days(&self) -> f64

as_mjd_days creates an Epoch from the provided Modified Julian Date in days as explained here. MJD epoch is Modified Julian Day at 17 November 1858 at midnight. :rtype: float

pub fn to_mjd_tai_seconds(&self) -> f64

Returns the Modified Julian Date in seconds TAI. :rtype: float

pub fn to_mjd_tai(&self, unit: Unit) -> f64

Returns this epoch as a duration in the requested units in MJD TAI :type unit: Unit :rtype: float

pub fn to_mjd_utc_days(&self) -> f64

Returns the Modified Julian Date in days UTC. :rtype: float

pub fn to_mjd_utc(&self, unit: Unit) -> f64

Returns the Modified Julian Date in the provided unit in UTC. :type unit: Unit :rtype: float

pub fn to_mjd_utc_seconds(&self) -> f64

Returns the Modified Julian Date in seconds UTC. :rtype: float

pub fn to_jde_tai_days(&self) -> f64

Returns the Julian days from epoch 01 Jan -4713, 12:00 (noon) as explained in “Fundamentals of astrodynamics and applications”, Vallado et al. 4th edition, page 182, and on Wikipedia. :rtype: float

pub fn to_jde_tai(&self, unit: Unit) -> f64

Returns the Julian Days from epoch 01 Jan -4713 12:00 (noon) in desired Duration::Unit :type unit: Unit :rtype: float

pub fn to_jde_tai_duration(&self) -> Duration

Returns the Julian Days from epoch 01 Jan -4713 12:00 (noon) as a Duration :rtype: Duration

pub fn to_jde_tai_seconds(&self) -> f64

Returns the Julian seconds in TAI. :rtype: float

pub fn to_jde_utc_days(&self) -> f64

Returns the Julian days in UTC. :rtype: float

pub fn to_jde_utc_duration(&self) -> Duration

Returns the Julian days in UTC as a Duration :rtype: Duration

pub fn to_jde_utc_seconds(&self) -> f64

Returns the Julian Days in UTC seconds. :rtype: float

pub fn to_tt_seconds(&self) -> f64

Returns seconds past TAI epoch in Terrestrial Time (TT) (previously called Terrestrial Dynamical Time (TDT)) :rtype: float

pub fn to_tt_duration(&self) -> Duration

Returns Duration past TAI epoch in Terrestrial Time (TT). :rtype: Duration

pub fn to_tt_days(&self) -> f64

Returns days past TAI epoch in Terrestrial Time (TT) (previously called Terrestrial Dynamical Time (TDT)) :rtype: float

pub fn to_tt_centuries_j2k(&self) -> f64

Returns the centuries passed J2000 TT :rtype: float

pub fn to_tt_since_j2k(&self) -> Duration

Returns the duration past J2000 TT :rtype: Duration

pub fn to_jde_tt_days(&self) -> f64

Returns days past Julian epoch in Terrestrial Time (TT) (previously called Terrestrial Dynamical Time (TDT)) :rtype: float

pub fn to_jde_tt_duration(&self) -> Duration

:rtype: Duration

pub fn to_mjd_tt_days(&self) -> f64

Returns days past Modified Julian epoch in Terrestrial Time (TT) (previously called Terrestrial Dynamical Time (TDT)) :rtype: float

pub fn to_mjd_tt_duration(&self) -> Duration

:rtype: Duration

pub fn to_gpst_seconds(&self) -> f64

Returns seconds past GPS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). :rtype: float

pub fn to_gpst_duration(&self) -> Duration

Returns Duration past GPS time Epoch. :rtype: Duration

pub fn to_gpst_nanoseconds(&self) -> Result<u64, HifitimeError>

Returns nanoseconds past GPS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). NOTE: This function will return an error if the centuries past GPST time are not zero. :rtype: int

pub fn to_gpst_days(&self) -> f64

Returns days past GPS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). :rtype: float

pub fn to_qzsst_seconds(&self) -> f64

Returns seconds past QZSS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). :rtype: float

pub fn to_qzsst_duration(&self) -> Duration

Returns Duration past QZSS time Epoch. :rtype: Duration

pub fn to_qzsst_nanoseconds(&self) -> Result<u64, HifitimeError>

Returns nanoseconds past QZSS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). NOTE: This function will return an error if the centuries past QZSST time are not zero. :rtype: int

pub fn to_qzsst_days(&self) -> f64

Returns days past QZSS Time Epoch, defined as UTC midnight of January 5th to 6th 1980 (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS#GPS_Time_.28GPST.29). :rtype: float

pub fn to_gst_seconds(&self) -> f64

Returns seconds past GST (Galileo) Time Epoch :rtype: float

pub fn to_gst_duration(&self) -> Duration

Returns Duration past GST (Galileo) time Epoch. :rtype: Duration

pub fn to_gst_nanoseconds(&self) -> Result<u64, HifitimeError>

Returns nanoseconds past GST (Galileo) Time Epoch, starting on August 21st 1999 Midnight UT (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS). NOTE: This function will return an error if the centuries past GST time are not zero. :rtype: int

pub fn to_gst_days(&self) -> f64

Returns days past GST (Galileo) Time Epoch, starting on August 21st 1999 Midnight UT (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS). :rtype: float

pub fn to_bdt_seconds(&self) -> f64

Returns seconds past BDT (BeiDou) Time Epoch :rtype: float

pub fn to_bdt_duration(&self) -> Duration

Returns Duration past BDT (BeiDou) time Epoch. :rtype: Duration

pub fn to_bdt_days(&self) -> f64

Returns days past BDT (BeiDou) Time Epoch, defined as Jan 01 2006 UTC (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS). :rtype: float

pub fn to_bdt_nanoseconds(&self) -> Result<u64, HifitimeError>

Returns nanoseconds past BDT (BeiDou) Time Epoch, defined as Jan 01 2006 UTC (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS). NOTE: This function will return an error if the centuries past GST time are not zero. :rtype: int

pub fn to_unix(&self, unit: Unit) -> f64

Returns the duration since the UNIX epoch in the provided unit. :type unit: Unit :rtype: float

pub fn to_unix_seconds(&self) -> f64

Returns the number seconds since the UNIX epoch defined 01 Jan 1970 midnight UTC. :rtype: float

pub fn to_unix_milliseconds(&self) -> f64

Returns the number milliseconds since the UNIX epoch defined 01 Jan 1970 midnight UTC. :rtype: float

pub fn to_unix_days(&self) -> f64

Returns the number days since the UNIX epoch defined 01 Jan 1970 midnight UTC. :rtype: float

pub fn to_et_seconds(&self) -> f64

Returns the Ephemeris Time seconds past 2000 JAN 01 midnight, matches NASA/NAIF SPICE. :rtype: float

pub fn to_et_duration(&self) -> Duration

Returns the duration between J2000 and the current epoch as per NAIF SPICE.

Warning

The et2utc function of NAIF SPICE will assume that there are 9 leap seconds before 01 JAN 1972, as this date introduces 10 leap seconds. At the time of writing, this does not seem to be in line with IERS and the documentation in the leap seconds list.

In order to match SPICE, the as_et_duration() function will manually get rid of that difference. :rtype: Duration

pub fn to_tdb_duration(&self) -> Duration

Returns the Dynamics Barycentric Time (TDB) as a high precision Duration since J2000

Algorithm

Given the embedded sine functions in the equation to compute the difference between TDB and TAI from the number of TDB seconds past J2000, one cannot solve the revert the operation analytically. Instead, we iterate until the value no longer changes.

1. Assume that the TAI duration is in fact the TDB seconds from J2000.
2. Offset to J2000 because Epoch stores everything in the J1900 but the TDB duration is in J2000.
3. Compute the offset g due to the TDB computation with the current value of the TDB seconds (defined in step 1).
4. Subtract that offset to the latest TDB seconds and store this as a new candidate for the true TDB seconds value.
5. Compute the difference between this candidate and the previous one. If the difference is less than one nanosecond, stop iteration.
6. Set the new candidate as the TDB seconds since J2000 and loop until step 5 breaks the loop, or we’ve done five iterations.
7. At this stage, we have a good approximation of the TDB seconds since J2000.
8. Reverse the algorithm given that approximation: compute the g offset, compute the difference between TDB and TAI, add the TT offset (32.184 s), and offset by the difference between J1900 and J2000.

:rtype: Duration

pub fn to_tdb_seconds(&self) -> f64

Returns the Dynamic Barycentric Time (TDB) (higher fidelity SPICE ephemeris time) whose epoch is 2000 JAN 01 noon TAI (cf. https://gssc.esa.int/navipedia/index.php/Transformations_between_Time_Systems#TDT_-_TDB.2C_TCB) :rtype: float

pub fn to_jde_et_days(&self) -> f64

Returns the Ephemeris Time JDE past epoch :rtype: float

pub fn to_jde_et_duration(&self) -> Duration

:rtype: Duration

pub fn to_jde_et(&self, unit: Unit) -> f64

:type unit: Unit :rtype: float

pub fn to_jde_tdb_duration(&self) -> Duration

:rtype: Duration

pub fn to_jde_tdb_days(&self) -> f64

Returns the Dynamic Barycentric Time (TDB) (higher fidelity SPICE ephemeris time) whose epoch is 2000 JAN 01 noon TAI (cf. https://gssc.esa.int/navipedia/index.php/Transformations_between_Time_Systems#TDT_-_TDB.2C_TCB) :rtype: float

pub fn to_tdb_days_since_j2000(&self) -> f64

Returns the number of days since Dynamic Barycentric Time (TDB) J2000 (used for Archinal et al. rotations) :rtype: float

pub fn to_tdb_centuries_since_j2000(&self) -> f64

Returns the number of centuries since Dynamic Barycentric Time (TDB) J2000 (used for Archinal et al. rotations) :rtype: float

pub fn to_et_days_since_j2000(&self) -> f64

Returns the number of days since Ephemeris Time (ET) J2000 (used for Archinal et al. rotations) :rtype: float

pub fn to_et_centuries_since_j2000(&self) -> f64

Returns the number of centuries since Ephemeris Time (ET) J2000 (used for Archinal et al. rotations) :rtype: float

pub fn duration_in_year(&self) -> Duration

Returns the duration since the start of the year :rtype: Duration

pub fn day_of_year(&self) -> f64

Returns the number of days since the start of the year. :rtype: float

pub fn year(&self) -> i32

Returns the number of Gregorian years of this epoch in the current time scale. :rtype: int

pub fn year_days_of_year(&self) -> (i32, f64)

Returns the year and the days in the year so far (days of year). :rtype: typing.Tuple

pub fn hours(&self) -> u64

Returns the hours of the Gregorian representation of this epoch in the time scale it was initialized in. :rtype: int

pub fn minutes(&self) -> u64

Returns the minutes of the Gregorian representation of this epoch in the time scale it was initialized in. :rtype: int

pub fn seconds(&self) -> u64

Returns the seconds of the Gregorian representation of this epoch in the time scale it was initialized in. :rtype: int

pub fn milliseconds(&self) -> u64

Returns the milliseconds of the Gregorian representation of this epoch in the time scale it was initialized in. :rtype: int

pub fn microseconds(&self) -> u64

Returns the microseconds of the Gregorian representation of this epoch in the time scale it was initialized in. :rtype: int

pub fn nanoseconds(&self) -> u64

Returns the nanoseconds of the Gregorian representation of this epoch in the time scale it was initialized in. :rtype: int

pub fn month_name(&self) -> MonthName

:rtype: MonthName

pub fn to_rfc3339(&self) -> String

Returns this epoch in UTC in the RFC3339 format :rtype: str

Trait Implementations

impl Add<Duration> for Epoch

type Output = Epoch

The resulting type after applying the + operator.

fn add(self, duration: Duration) -> Epoch

Performs the + operation.

impl Add<Unit> for Epoch

type Output = Epoch

The resulting type after applying the + operator.

fn add(self, unit: Unit) -> Epoch

Performs the + operation.

impl Add<f64> for Epoch

WARNING: For speed, there is a possibility to add seconds directly to an Epoch. These will be added in the time scale the Epoch was initialized in. Using this is discouraged and should only be used if you have facing bottlenecks with the units.

type Output = Epoch

The resulting type after applying the + operator.

fn add(self, seconds: f64) -> Epoch

Performs the + operation.

impl AddAssign<Duration> for Epoch

fn add_assign(&mut self, duration: Duration)

Performs the += operation.

impl AddAssign<Unit> for Epoch

fn add_assign(&mut self, unit: Unit)

Performs the += operation.

impl Clone for Epoch

fn clone(&self) -> Epoch

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

The default format of an epoch is in UTC

impl Default for Epoch

fn default() -> Epoch

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Epoch

fn deserialize<D>( deserializer: D, ) -> Result<Epoch, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Print this epoch in Gregorian in the time scale used at initialization

impl FromStr for Epoch

fn from_str(s_in: &str) -> Result<Epoch, <Epoch as FromStr>::Err>

Attempts to convert a string to an Epoch.

Format identifiers:

• JD: Julian days
• MJD: Modified Julian days
• SEC: Seconds past a given epoch (e.g. SEC 17.2 TAI is 17.2 seconds past TAI Epoch)

Example

use hifitime::Epoch;
use core::str::FromStr;

assert!(Epoch::from_str("JD 2452312.500372511 TDB").is_ok());
assert!(Epoch::from_str("JD 2452312.500372511 ET").is_ok());
assert!(Epoch::from_str("JD 2452312.500372511 TAI").is_ok());
assert!(Epoch::from_str("MJD 51544.5 TAI").is_ok());
assert!(Epoch::from_str("SEC 0.5 TAI").is_ok());
assert!(Epoch::from_str("SEC 66312032.18493909 TDB").is_ok());

type Err = HifitimeError

The associated error which can be returned from parsing.

impl Hash for Epoch

fn hash<H>(&self, state: &mut H)

where H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl LowerExp for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Prints the Epoch in TDB

impl LowerHex for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Prints the Epoch in TAI

impl Octal for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Prints the Epoch in GPS

impl Ord for Epoch

fn cmp(&self, other: &Epoch) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Epoch

Equality only checks the duration since J1900 match in TAI, because this is how all of the epochs are referenced.

fn eq(&self, other: &Epoch) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Epoch

fn partial_cmp(&self, other: &Epoch) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Pointer for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Prints the Epoch in UNIX

impl Serialize for Epoch

fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl Sub<Duration> for Epoch

type Output = Epoch

The resulting type after applying the - operator.

fn sub(self, duration: Duration) -> Epoch

Performs the - operation.

impl Sub<Unit> for Epoch

type Output = Epoch

The resulting type after applying the - operator.

fn sub(self, unit: Unit) -> Epoch

Performs the - operation.

impl Sub for Epoch

type Output = Duration

The resulting type after applying the - operator.

fn sub(self, other: Epoch) -> Duration

Performs the - operation.

impl SubAssign<Duration> for Epoch

fn sub_assign(&mut self, duration: Duration)

Performs the -= operation.

impl SubAssign<Unit> for Epoch

fn sub_assign(&mut self, unit: Unit)

Performs the -= operation.

impl UpperExp for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Prints the Epoch in ET

impl UpperHex for Epoch

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Prints the Epoch in TT

impl Copy for Epoch

impl Eq for Epoch