Module time

Classes

Class Duration

class Duration(
    string_repr
)

Defines generally usable durations for nanosecond precision valid for 32,768 centuries in either direction, and only on 80 bits / 10 octets.

Important conventions: 1. The negative durations can be mentally modeled "BC" years. One hours before 01 Jan 0000, it was "-1" years but 365 days and 23h into the current day. It was decided that the nanoseconds corresponds to the nanoseconds into the current century. In other words, a duration with centuries = -1 and nanoseconds = 0 is a greater duration (further from zero) than centuries = -1 and nanoseconds = 1. Duration zero minus one nanosecond returns a century of -1 and a nanosecond set to the number of nanoseconds in one century minus one. That difference is exactly 1 nanoseconds, where the former duration is "closer to zero" than the latter. As such, the largest negative duration that can be represented sets the centuries to i16::MAX and its nanoseconds to NANOSECONDS_PER_CENTURY. 2. It was also decided that opposite durations are equal, e.g. -15 minutes == 15 minutes. If the direction of time matters, use the signum function.

Methods

Method EPSILON

def EPSILON()

Method MAX

def MAX()

Method MIN

def MIN()

Method MIN_NEGATIVE

def MIN_NEGATIVE()

Method MIN_POSITIVE

def MIN_POSITIVE()

Method ZERO

def ZERO()

Method abs

def abs(
    self,
    /
)

Returns the absolute value of this duration

Method approx

def approx(
    self,
    /
)

Rounds this duration to the largest units represented in this duration.

This is useful to provide an approximate human duration. Under the hood, this function uses round, so the "tipping point" of the rounding is half way to the next increment of the greatest unit. As shown below, one example is that 35 hours and 59 minutes rounds to 1 day, but 36 hours and 1 minute rounds to 2 days because 2 days is closer to 36h 1 min than 36h 1 min is to 1 day.

Example

use hifitime::{Duration, TimeUnits};

assert_eq!((2.hours() + 3.minutes()).approx(), 2.hours());
assert_eq!((24.hours() + 3.minutes()).approx(), 1.days());
assert_eq!((35.hours() + 59.minutes()).approx(), 1.days());
assert_eq!((36.hours() + 1.minutes()).approx(), 2.days());
assert_eq!((47.hours() + 3.minutes()).approx(), 2.days());
assert_eq!((49.hours() + 3.minutes()).approx(), 2.days());

Method ceil

def ceil(
    self,
    /,
    duration
)

Ceils this duration to the closest provided duration

This simply floors then adds the requested duration

Example

use hifitime::{Duration, TimeUnits};

let two_hours_three_min = 2.hours() + 3.minutes();
assert_eq!(two_hours_three_min.ceil(1.hours()), 3.hours());
assert_eq!(two_hours_three_min.ceil(30.minutes()), 2.hours() + 30.minutes());
assert_eq!(two_hours_three_min.ceil(4.hours()), 4.hours());
assert_eq!(two_hours_three_min.ceil(1.seconds()), two_hours_three_min + 1.seconds());
assert_eq!(two_hours_three_min.ceil(1.hours() + 5.minutes()), 2.hours() + 10.minutes());

Method decompose

def decompose(
    self,
    /
)

Decomposes a Duration in its sign, days, hours, minutes, seconds, ms, us, ns

Method floor

def floor(
    self,
    /,
    duration
)

Floors this duration to the closest duration from the bottom

Example

use hifitime::{Duration, TimeUnits};

let two_hours_three_min = 2.hours() + 3.minutes();
assert_eq!(two_hours_three_min.floor(1.hours()), 2.hours());
assert_eq!(two_hours_three_min.floor(30.minutes()), 2.hours());
// This is zero because we floor by a duration longer than the current duration, rounding it down
assert_eq!(two_hours_three_min.floor(4.hours()), 0.hours());
assert_eq!(two_hours_three_min.floor(1.seconds()), two_hours_three_min);
assert_eq!(two_hours_three_min.floor(1.hours() + 1.minutes()), 2.hours() + 2.minutes());
assert_eq!(two_hours_three_min.floor(1.hours() + 5.minutes()), 1.hours() + 5.minutes());

Method from_all_parts

def from_all_parts(
    sign,
    days,
    hours,
    minutes,
    seconds,
    milliseconds,
    microseconds,
    nanoseconds
)

Creates a new duration from its parts

Method from_parts

def from_parts(
    centuries,
    nanoseconds
)

Create a normalized duration from its parts

Method from_total_nanoseconds

def from_total_nanoseconds(
    nanos
)

Method is_negative

def is_negative(
    self,
    /
)

Returns whether this is a negative or positive duration.

Method max

def max(
    self,
    /,
    other
)

Returns the maximum of the two durations.

use hifitime::TimeUnits;

let d0 = 20.seconds();
let d1 = 21.seconds();

assert_eq!(d1, d1.max(d0));
assert_eq!(d1, d0.max(d1));

Method min

def min(
    self,
    /,
    other
)

Returns the minimum of the two durations.

use hifitime::TimeUnits;

let d0 = 20.seconds();
let d1 = 21.seconds();

assert_eq!(d0, d1.min(d0));
assert_eq!(d0, d0.min(d1));

Method round

def round(
    self,
    /,
    duration
)

Rounds this duration to the closest provided duration

This performs both a ceil and floor and returns the value which is the closest to current one.

Example

use hifitime::{Duration, TimeUnits};

let two_hours_three_min = 2.hours() + 3.minutes();
assert_eq!(two_hours_three_min.round(1.hours()), 2.hours());
assert_eq!(two_hours_three_min.round(30.minutes()), 2.hours());
assert_eq!(two_hours_three_min.round(4.hours()), 4.hours());
assert_eq!(two_hours_three_min.round(1.seconds()), two_hours_three_min);
assert_eq!(two_hours_three_min.round(1.hours() + 5.minutes()), 2.hours() + 10.minutes());

Method signum

def signum(
    self,
    /
)

Returns the sign of this duration + 0 if the number is zero + 1 if the number is positive + -1 if the number is negative

Method to_parts

def to_parts(
    self,
    /
)

Returns the centuries and nanoseconds of this duration NOTE: These items are not public to prevent incorrect durations from being created by modifying the values of the structure directly.

Method to_seconds

def to_seconds(
    self,
    /
)

Returns this duration in seconds f64. For high fidelity comparisons, it is recommended to keep using the Duration structure.

Method to_unit

def to_unit(
    self,
    /,
    unit
)

Method total_nanoseconds

def total_nanoseconds(
    self,
    /
)

Returns the total nanoseconds in a signed 128 bit integer

Class Epoch

class Epoch(
    string_repr
)

Defines a nanosecond-precision Epoch.

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

Methods

Method day_of_year

def day_of_year(
    self,
    /
)

Returns the number of days since the start of the year.

Method duration_in_year

def duration_in_year(
    self,
    /
)

Returns the duration since the start of the year

Method hours

def hours(
    self,
    /
)

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

Method init_from_bdt_days

def init_from_bdt_days(
    days
)

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

Method init_from_bdt_nanoseconds

def init_from_bdt_nanoseconds(
    nanoseconds
)

Initialize an Epoch from the number of days since the BeiDou Time Epoch, defined as 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.

Method init_from_bdt_seconds

def init_from_bdt_seconds(
    seconds
)

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

Method init_from_et_duration

def init_from_et_duration(
    duration_since_j2000
)

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

Method init_from_et_seconds

def init_from_et_seconds(
    seconds_since_j2000
)

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

Method init_from_gpst_days

def init_from_gpst_days(
    days
)

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).

Method init_from_gpst_nanoseconds

def init_from_gpst_nanoseconds(
    nanoseconds
)

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.

Method init_from_gpst_seconds

def init_from_gpst_seconds(
    seconds
)

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).

Method init_from_gregorian

def init_from_gregorian(
    year,
    month,
    day,
    hour,
    minute,
    second,
    nanos,
    time_scale
)

Method init_from_gregorian_at_midnight

def init_from_gregorian_at_midnight(
    year,
    month,
    day,
    time_scale
)

Method init_from_gregorian_at_noon

def init_from_gregorian_at_noon(
    year,
    month,
    day,
    time_scale
)

Method init_from_gregorian_tai

def init_from_gregorian_tai(
    year,
    month,
    day,
    hour,
    minute,
    second,
    nanos
)

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.

Method init_from_gregorian_tai_at_midnight

def init_from_gregorian_tai_at_midnight(
    year,
    month,
    day
)

Initialize from the Gregorian date at midnight in TAI.

Method init_from_gregorian_tai_at_noon

def init_from_gregorian_tai_at_noon(
    year,
    month,
    day
)

Initialize from the Gregorian date at noon in TAI

Method init_from_gregorian_tai_hms

def init_from_gregorian_tai_hms(
    year,
    month,
    day,
    hour,
    minute,
    second
)

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

Method init_from_gregorian_utc

def init_from_gregorian_utc(
    year,
    month,
    day,
    hour,
    minute,
    second,
    nanos
)

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.

Method init_from_gregorian_utc_at_midnight

def init_from_gregorian_utc_at_midnight(
    year,
    month,
    day
)

Initialize from Gregorian date in UTC at midnight

Method init_from_gregorian_utc_at_noon

def init_from_gregorian_utc_at_noon(
    year,
    month,
    day
)

Initialize from Gregorian date in UTC at noon

Method init_from_gregorian_utc_hms

def init_from_gregorian_utc_hms(
    year,
    month,
    day,
    hour,
    minute,
    second
)

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

Method init_from_gst_days

def init_from_gst_days(
    days
)

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

Method init_from_gst_nanoseconds

def init_from_gst_nanoseconds(
    nanoseconds
)

Initialize an Epoch from the number of nanoseconds since the Galileo Time Epoch, starting on August 21st 1999 Midnight UT, (cf. https://gssc.esa.int/navipedia/index.php/Time_References_in_GNSS). This may be useful for time keeping devices that use GST as a time source.

Method init_from_gst_seconds

def init_from_gst_seconds(
    seconds
)

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

Method init_from_jde_et

def init_from_jde_et(
    days
)

Initialize from the JDE days

Method init_from_jde_tai

def init_from_jde_tai(
    days
)

Initialize an Epoch from given JDE in TAI time scale

Method init_from_jde_tdb

def init_from_jde_tdb(
    days
)

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

Method init_from_jde_utc

def init_from_jde_utc(
    days
)

Initialize an Epoch from given JDE in UTC time scale

Method init_from_mjd_tai

def init_from_mjd_tai(
    days
)

Initialize an Epoch from given MJD in TAI time scale

Method init_from_mjd_utc

def init_from_mjd_utc(
    days
)

Initialize an Epoch from given MJD in UTC time scale

Method init_from_qzsst_days

def init_from_qzsst_days(
    days
)

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).

Method init_from_qzsst_nanoseconds

def init_from_qzsst_nanoseconds(
    nanoseconds
)

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.

Method init_from_qzsst_seconds

def init_from_qzsst_seconds(
    seconds
)

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).

Method init_from_tai_days

def init_from_tai_days(
    days
)

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

Method init_from_tai_duration

def init_from_tai_duration(
    duration
)

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

Method init_from_tai_parts

def init_from_tai_parts(
    centuries,
    nanoseconds
)

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

Method init_from_tai_seconds

def init_from_tai_seconds(
    seconds
)

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

Method init_from_tdb_duration

def init_from_tdb_duration(
    duration_since_j2000
)

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

Method init_from_tdb_seconds

def init_from_tdb_seconds(
    seconds_j2000
)

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.

Method init_from_tt_duration

def init_from_tt_duration(
    duration
)

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

Method init_from_tt_seconds

def init_from_tt_seconds(
    seconds
)

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

Method init_from_unix_milliseconds

def init_from_unix_milliseconds(
    milliseconds
)

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

Method init_from_unix_seconds

def init_from_unix_seconds(
    seconds
)

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

Method init_from_utc_days

def init_from_utc_days(
    days
)

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

Method init_from_utc_seconds

def init_from_utc_seconds(
    seconds
)

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

Method isoformat

def isoformat(
    self,
    /
)

Equivalent to datetime.isoformat, and truncated to 23 chars, refer to https://docs.rs/hifitime/latest/hifitime/efmt/format/struct.Format.html for format options

Method leap_seconds

def leap_seconds(
    self,
    /,
    iers_only
)

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.

Method leap_seconds_iers

def leap_seconds_iers(
    self,
    /
)

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

Method leap_seconds_with_file

def leap_seconds_with_file(
    self,
    /,
    iers_only,
    provider
)

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.

Method maybe_init_from_gregorian

def maybe_init_from_gregorian(
    year,
    month,
    day,
    hour,
    minute,
    second,
    nanos,
    time_scale
)

Attempts to build an Epoch from the provided Gregorian date and time in the provided time scale. NOTE: If the time scale is TDB, this function assumes that the SPICE format is used

Method maybe_init_from_gregorian_tai

def maybe_init_from_gregorian_tai(
    year,
    month,
    day,
    hour,
    minute,
    second,
    nanos
)

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

Method maybe_init_from_gregorian_utc

def maybe_init_from_gregorian_utc(
    year,
    month,
    day,
    hour,
    minute,
    second,
    nanos
)

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

Method microseconds

def microseconds(
    self,
    /
)

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

Method milliseconds

def milliseconds(
    self,
    /
)

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

Method minutes

def minutes(
    self,
    /
)

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

Method month_name

def month_name(
    self,
    /
)

Method nanoseconds

def nanoseconds(
    self,
    /
)

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

Method seconds

def seconds(
    self,
    /
)

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

Method strftime

def strftime(
    self,
    /,
    format_str
)

Equivalent to datetime.strftime, refer to https://docs.rs/hifitime/latest/hifitime/efmt/format/struct.Format.html for format options

Method strptime

def strptime(
    epoch_str,
    format_str
)

Equivalent to datetime.strptime, refer to https://docs.rs/hifitime/latest/hifitime/efmt/format/struct.Format.html for format options

Method system_now

def system_now()

Method timedelta

def timedelta(
    self,
    /,
    other
)

Method to_bdt_days

def to_bdt_days(
    self,
    /
)

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).

Method to_bdt_duration

def to_bdt_duration(
    self,
    /
)

Returns Duration past BDT (BeiDou) time Epoch.

Method to_bdt_nanoseconds

def to_bdt_nanoseconds(
    self,
    /
)

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.

Method to_bdt_seconds

def to_bdt_seconds(
    self,
    /
)

Returns seconds past BDT (BeiDou) Time Epoch

Method to_duration_in_time_scale

def to_duration_in_time_scale(
    self,
    /,
    ts
)

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).

Method to_et_centuries_since_j2000

def to_et_centuries_since_j2000(
    self,
    /
)

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

Method to_et_days_since_j2000

def to_et_days_since_j2000(
    self,
    /
)

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

Method to_et_duration

def to_et_duration(
    self,
    /
)

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.

Method to_et_seconds

def to_et_seconds(
    self,
    /
)

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

Method to_gpst_days

def to_gpst_days(
    self,
    /
)

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).

Method to_gpst_duration

def to_gpst_duration(
    self,
    /
)

Returns Duration past GPS time Epoch.

Method to_gpst_nanoseconds

def to_gpst_nanoseconds(
    self,
    /
)

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.

Method to_gpst_seconds

def to_gpst_seconds(
    self,
    /
)

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).

Method to_gst_days

def to_gst_days(
    self,
    /
)

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).

Method to_gst_duration

def to_gst_duration(
    self,
    /
)

Returns Duration past GST (Galileo) time Epoch.

Method to_gst_nanoseconds

def to_gst_nanoseconds(
    self,
    /
)

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.

Method to_gst_seconds

def to_gst_seconds(
    self,
    /
)

Returns seconds past GST (Galileo) Time Epoch

Method to_isoformat

def to_isoformat(
    self,
    /
)

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.

Method to_jde_et

def to_jde_et(
    self,
    /,
    unit
)

Method to_jde_et_days

def to_jde_et_days(
    self,
    /
)

Returns the Ephemeris Time JDE past epoch

Method to_jde_et_duration

def to_jde_et_duration(
    self,
    /
)

Method to_jde_tai

def to_jde_tai(
    self,
    /,
    unit
)

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

Method to_jde_tai_days

def to_jde_tai_days(
    self,
    /
)

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.

Method to_jde_tai_duration

def to_jde_tai_duration(
    self,
    /
)

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

Method to_jde_tai_seconds

def to_jde_tai_seconds(
    self,
    /
)

Returns the Julian seconds in TAI.

Method to_jde_tdb_days

def to_jde_tdb_days(
    self,
    /
)

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)

Method to_jde_tdb_duration

def to_jde_tdb_duration(
    self,
    /
)

Method to_jde_tt_days

def to_jde_tt_days(
    self,
    /
)

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

Method to_jde_tt_duration

def to_jde_tt_duration(
    self,
    /
)

Method to_jde_utc_days

def to_jde_utc_days(
    self,
    /
)

Returns the Julian days in UTC.

Method to_jde_utc_duration

def to_jde_utc_duration(
    self,
    /
)

Returns the Julian days in UTC as a Duration

Method to_jde_utc_seconds

def to_jde_utc_seconds(
    self,
    /
)

Returns the Julian Days in UTC seconds.

Method to_mjd_tai

def to_mjd_tai(
    self,
    /,
    unit
)

Returns this epoch as a duration in the requested units in MJD TAI

Method to_mjd_tai_days

def to_mjd_tai_days(
    self,
    /
)

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.

Method to_mjd_tai_seconds

def to_mjd_tai_seconds(
    self,
    /
)

Returns the Modified Julian Date in seconds TAI.

Method to_mjd_tt_days

def to_mjd_tt_days(
    self,
    /
)

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

Method to_mjd_tt_duration

def to_mjd_tt_duration(
    self,
    /
)

Method to_mjd_utc

def to_mjd_utc(
    self,
    /,
    unit
)

Returns the Modified Julian Date in the provided unit in UTC.

Method to_mjd_utc_days

def to_mjd_utc_days(
    self,
    /
)

Returns the Modified Julian Date in days UTC.

Method to_mjd_utc_seconds

def to_mjd_utc_seconds(
    self,
    /
)

Returns the Modified Julian Date in seconds UTC.

Method to_nanoseconds_in_time_scale

def to_nanoseconds_in_time_scale(
    self,
    /,
    time_scale
)

Attempts to return the number of nanoseconds since the reference epoch of the provided time scale. This will return an overflow error if more than one century has past since the reference epoch in the provided time scale. If this is not an issue, you should use epoch.to_duration_in_time_scale().to_parts() to retrieve both the centuries and the nanoseconds in that century.

Method to_qzsst_days

def to_qzsst_days(
    self,
    /
)

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).

Method to_qzsst_duration

def to_qzsst_duration(
    self,
    /
)

Returns Duration past QZSS time Epoch.

Method to_qzsst_nanoseconds

def to_qzsst_nanoseconds(
    self,
    /
)

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.

Method to_qzsst_seconds

def to_qzsst_seconds(
    self,
    /
)

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).

Method to_rfc3339

def to_rfc3339(
    self,
    /
)

Returns this epoch in UTC in the RFC3339 format

Method to_tai

def to_tai(
    self,
    /,
    unit
)

Returns the epoch as a floating point value in the provided unit

Method to_tai_days

def to_tai_days(
    self,
    /
)

Returns the number of days since J1900 in TAI

Method to_tai_duration

def to_tai_duration(
    self,
    /
)

Returns this time in a Duration past J1900 counted in TAI

Method to_tai_parts

def to_tai_parts(
    self,
    /
)

Returns the TAI parts of this duration

Method to_tai_seconds

def to_tai_seconds(
    self,
    /
)

Returns the number of TAI seconds since J1900

Method to_tdb_centuries_since_j2000

def to_tdb_centuries_since_j2000(
    self,
    /
)

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

Method to_tdb_days_since_j2000

def to_tdb_days_since_j2000(
    self,
    /
)

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

Method to_tdb_duration

def to_tdb_duration(
    self,
    /
)

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.

Method to_tdb_seconds

def to_tdb_seconds(
    self,
    /
)

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)

Method to_tt_centuries_j2k

def to_tt_centuries_j2k(
    self,
    /
)

Returns the centuries passed J2000 TT

Method to_tt_days

def to_tt_days(
    self,
    /
)

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

Method to_tt_duration

def to_tt_duration(
    self,
    /
)

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

Method to_tt_seconds

def to_tt_seconds(
    self,
    /
)

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

Method to_tt_since_j2k

def to_tt_since_j2k(
    self,
    /
)

Returns the duration past J2000 TT

Method to_unix

def to_unix(
    self,
    /,
    unit
)

Returns the duration since the UNIX epoch in the provided unit.

Method to_unix_days

def to_unix_days(
    self,
    /
)

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

Method to_unix_duration

def to_unix_duration(
    self,
    /
)

Returns the Duration since the UNIX epoch UTC midnight 01 Jan 1970.

Method to_unix_milliseconds

def to_unix_milliseconds(
    self,
    /
)

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

Method to_unix_seconds

def to_unix_seconds(
    self,
    /
)

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

Method to_utc

def to_utc(
    self,
    /,
    unit
)

Returns the number of UTC seconds since the TAI epoch

Method to_utc_days

def to_utc_days(
    self,
    /
)

Returns the number of UTC days since the TAI epoch

Method to_utc_duration

def to_utc_duration(
    self,
    /
)

Returns this time in a Duration past J1900 counted in UTC

Method to_utc_seconds

def to_utc_seconds(
    self,
    /
)

Returns the number of UTC seconds since the TAI epoch

Method year

def year(
    self,
    /
)

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

Method year_days_of_year

def year_days_of_year(
    self,
    /
)

Returns the year and the days in the year so far (days of year).

Class LatestLeapSeconds

class LatestLeapSeconds

List of leap seconds from https://www.ietf.org/timezones/data/leap-seconds.list . This list corresponds the number of seconds in TAI to the UTC offset and to whether it was an announced leap second or not. The unannoucned leap seconds come from dat.c in the SOFA library.

Class LeapSecondsFile

class LeapSecondsFile(
    path
)

A leap second provider that uses an IERS formatted leap seconds file.

Class TimeScale

class TimeScale(
    ...
)

Enum of the different time systems available

Class variables

Variable BDT

Variable ET

Variable GPST

Variable GST

Variable QZSST

Variable TAI

Variable TDB

Variable TT

Variable UTC

Methods

Method uses_leap_seconds

def uses_leap_seconds(
    self,
    /
)

Returns true if self takes leap seconds into account

Class TimeSeries

class TimeSeries(
    start,
    end,
    step,
    inclusive
)

An iterator of a sequence of evenly spaced Epochs.

Class Unit

class Unit(
    ...
)

An Enum to perform time unit conversions.

Class variables

Variable Century

Variable Day

Variable Hour

Variable Microsecond

Variable Millisecond

Variable Minute

Variable Nanosecond

Variable Second

Variable Week

Methods

Method from_seconds

def from_seconds(
    self,
    /
)

Method in_seconds

def in_seconds(
    self,
    /
)

Class Ut1Provider

class Ut1Provider

A structure storing all of the TAI-UT1 data

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