# Module anise.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 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.

##### Method ceil¶
def ceil(
self,
/,
duration
)


Ceils this duration to the closest provided duration

This simply floors then adds the requested duration

##### Method decompose¶
def decompose(
self,
/
)


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

##### Method epsilon¶
def epsilon()

##### Method floor¶
def floor(
self,
/,
duration
)


Floors this duration to the closest duration from the bottom

##### Method init_from_all_parts¶
def init_from_all_parts(
sign,
days,
hours,
minutes,
seconds,
milliseconds,
microseconds,
nanoseconds
)


Creates a new duration from its parts

##### Method init_from_max¶
def init_from_max()

##### Method init_from_min¶
def init_from_min()

##### Method init_from_parts¶
def init_from_parts(
centuries,
nanoseconds
)


Create a normalized duration from its parts

##### Method init_from_total_nanoseconds¶
def init_from_total_nanoseconds(
nanos
)

##### Method init_from_truncated_nanoseconds¶
def init_from_truncated_nanoseconds(
nanos
)


Create a new duration from the truncated nanoseconds (+/- 2927.1 years of duration)

##### 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));


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

##### 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));


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

##### Method min_negative¶
def min_negative()

##### Method min_positive¶
def min_positive()

##### Method normalize¶
def normalize(
self,
/
)

##### 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.

##### 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

##### Method truncated_nanoseconds¶
def truncated_nanoseconds(
self,
/
)


Returns the truncated nanoseconds in a signed 64 bit integer, if the duration fits. WARNING: This function will NOT fail and will return the i64::MIN or i64::MAX depending on the sign of the centuries if the Duration does not fit on aa i64

##### Method try_truncated_nanoseconds¶
def try_truncated_nanoseconds(
self,
/
)


Returns the truncated nanoseconds in a signed 64 bit integer, if the duration fits.

##### Method zero¶
def zero()


### 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 ceil¶
def ceil(
self,
/,
duration
)


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

##### 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 floor¶
def floor(
self,
/,
duration
)


Floors this epoch to the closest provided duration

##### Method hours¶
def hours(
self,
/
)


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

##### Method in_time_scale¶
def in_time_scale(
self,
/,
new_time_scale
)


Copies this epoch and sets it to the new time scale provided.

##### 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_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.

##### 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.

##### Method max¶
def max(
self,
/,
other
)


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.

##### 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 min¶
def min(
self,
/,
other
)


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.

##### 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 next¶
def next(
self,
/,
weekday
)


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));

##### Method next_weekday_at_midnight¶
def next_weekday_at_midnight(
self,
/,
weekday
)

##### Method next_weekday_at_noon¶
def next_weekday_at_noon(
self,
/,
weekday
)

##### Method previous¶
def previous(
self,
/,
weekday
)


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));

##### Method previous_weekday_at_midnight¶
def previous_weekday_at_midnight(
self,
/,
weekday
)

##### Method previous_weekday_at_noon¶
def previous_weekday_at_noon(
self,
/,
weekday
)

##### Method round¶
def round(
self,
/,
duration
)


Rounds this epoch to the closest provided duration in TAI

##### Method seconds¶
def seconds(
self,
/
)


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

##### Method set¶
def set(
self,
/,
new_duration
)


Makes a copy of self and sets the duration and time scale appropriately given the new duration

##### 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¶
def to_duration(
self,
/
)


Returns this epoch with respect to the time scale this epoch was created in. This is needed to correctly perform duration conversions in dynamical time scales (e.g. TDB).

###### Examples¶
1. If an epoch was initialized as Epoch.init_from_..._utc(...) then the duration will be the UTC duration from J1900.
2. If an epoch was initialized as Epoch.init_from_..._tdb(...) then the duration will be the UTC duration from J2000 because the TDB reference epoch is J2000.
##### Method to_duration_in_time_scale¶
def to_duration_in_time_scale(
self,
/,
time_scale
)


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_duration_since_j1900¶
def to_duration_since_j1900(
self,
/
)


Returns this epoch in duration since J1900 in the time scale this epoch was created in.

##### Method to_duration_since_j1900_in_time_scale¶
def to_duration_since_j1900_in_time_scale(
self,
/,
time_scale
)


Returns this epoch in duration since J1900 with respect to the provided time scale.

##### 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_duration_since_j1900¶
def to_et_duration_since_j1900(
self,
/
)


Returns the Ephemeris Time in duration past 1900 JAN 01 at noon. Only use this if the subsequent computation expect J1900 seconds.

##### 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_gregorian_str¶
def to_gregorian_str(
self,
/,
time_scale
)


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

##### Method to_gregorian_tai¶
def to_gregorian_tai(
self,
/
)


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

##### Method to_gregorian_tai_str¶
def to_gregorian_tai_str(
self,
/
)


Converts the Epoch to TAI Gregorian in the ISO8601 format with " TAI" appended to the string

##### Method to_gregorian_utc¶
def to_gregorian_utc(
self,
/
)


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

##### Method to_gregorian_utc_str¶
def to_gregorian_utc_str(
self,
/
)


Converts the Epoch to UTC Gregorian in the ISO8601 format.

##### 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), 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_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_duration_since_j1900¶
def to_tdb_duration_since_j1900(
self,
/
)


Returns the Dynamics Barycentric Time (TDB) as a high precision Duration with reference epoch of 1900 JAN 01 at noon. Only use this if the subsequent computation expect J1900 seconds.

##### 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_time_of_week¶
def to_time_of_week(
self,
/
)


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.

##### 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_ut1¶
def to_ut1(
self,
/,
provider
)


Returns this time in a Duration past J1900 counted in UT1

##### Method to_ut1_duration¶
def to_ut1_duration(
self,
/,
provider
)


Returns this time in a Duration past J1900 counted in UT1

##### 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 ut1_offset¶
def ut1_offset(
self,
/,
provider
)


Get the accumulated offset between this epoch and UT1, assuming that the provider includes all data.

##### Method weekday¶
def weekday(
self,
/
)


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

##### Method weekday_in_time_scale¶
def weekday_in_time_scale(
self,
/,
time_scale
)


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.

##### Method weekday_utc¶
def weekday_utc(
self,
/
)


Returns weekday in UTC timescale

##### Method with_hms¶
def with_hms(
self,
/,
hours,
minutes,
seconds
)


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.

##### Method with_hms_from¶
def with_hms_from(
self,
/,
other
)


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.in_time_scale(TimeScale::TDB);

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

##### Method with_hms_strict¶
def with_hms_strict(
self,
/,
hours,
minutes,
seconds
)


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.

##### Method with_hms_strict_from¶
def with_hms_strict_from(
self,
/,
other
)


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.in_time_scale(TimeScale::TDB);

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

##### Method with_time_from¶
def with_time_from(
self,
/,
other
)


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.in_time_scale(TimeScale::TDB);

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

##### 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

#### 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.

#### 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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