time

Utilities for calculating time operations

Can convert delta time from seconds since an epoch to time since a different epoch

Can calculate the time in days since epoch from calendar dates

Can count the number of leap seconds between a given GPS time and UTC

Syncs leap second files with NIST servers

Calling Sequence

Count the number of leap seconds between a GPS time and UTC

import SMBcorr.time
leap_seconds = SMBcorr.time.count_leap_seconds(gps_seconds)

Convert a time from seconds since 1980-01-06T00:00:00 to Modified Julian Days (MJD)

import SMBcorr.time
MJD = SMBcorr.time.convert_delta_time(delta_time, epoch1=(1980,1,6,0,0,0),
    epoch2=(1858,11,17,0,0,0), scale=1.0/86400.0)

Convert a calendar date into Modified Julian Days

import SMBcorr.time
MJD = SMBcorr.time.convert_calendar_dates(YEAR,MONTH,DAY,hour=HOUR,
    minute=MINUTE,second=SECOND,epoch=(1858,11,17,0,0,0))

Source code

General Methods

SMBcorr.time.parse_date_string(date_string)[source]

parse a date string of the form

time-units since yyyy-mm-dd hh:mm:ss
yyyy-mm-dd hh:mm:ss for exact calendar dates

Parameters:

date_string: str: time-units since yyyy-mm-dd hh:mm:ss

Returns:

epoch: list: epoch of delta time
conversion_factor: float: multiplication factor to convert to seconds

SMBcorr.time.split_date_string(date_string)[source]

split a date string into units and epoch

Parameters:

date_string: str: time-units since yyyy-mm-dd hh:mm:ss

SMBcorr.time.datetime_to_list(date)[source]

convert a datetime object into a list

Parameters:

date: datetime object

Returns:

date: list: [year,month,day,hour,minute,second]

SMBcorr.time.calendar_days(year)[source]

Calculates the number of days per month for a given year

Parameters:

year: int or float: calendar year

Returns:

dpm: list: number of days for each month

SMBcorr.time.convert_datetime(date, epoch=(1970, 1, 1, 0, 0, 0))[source]

Convert a numpy datetime array to seconds since epoch

Parameters:

date: obj: numpy datetime array
epoch: tuple, default (1970,1,1,0,0,0): epoch for output delta_time

Returns:

delta_time: float: seconds since epoch

SMBcorr.time.convert_delta_time(delta_time, epoch1=None, epoch2=None, scale=1.0)[source]

Convert delta time from seconds since epoch1 to time since epoch2

Parameters:

delta_time: float: seconds since epoch1
epoch1: tuple or NoneType, default None: epoch for input delta_time
epoch2: tuple or NoneType, default None: epoch for output delta_time
scale: float, default 1.0: scaling factor for converting time to output units

SMBcorr.time.convert_calendar_dates(year, month, day, hour=0.0, minute=0.0, second=0.0, epoch=(1992, 1, 1, 0, 0, 0), scale=1.0)[source]

Calculate the time in time units since epoch from calendar dates

Parameters:

year: float: calendar year
month: float: month of the year
day: float: day of the month
hour: float, default 0.0: hour of the day
minute: float, default 0.0: minute of the hour
second: float, default 0.0: second of the minute
epoch: tuple, default (1992,1,1,0,0,0): epoch for output delta_time
scale: float, default 1.0: scaling factor for converting time to output units

Returns:

delta_time: float: days since epoch

SMBcorr.time.convert_calendar_decimal(year, month, day=None, hour=None, minute=None, second=None, DofY=None)[source]

Converts from calendar date into decimal years taking into account leap years

Parameters:

year: float: calendar year
month: float: calendar month
day: float or NoneType, default None: day of the month
hour: float or NoneType, default None: hour of the day
minute: float or NoneType, default None: minute of the hour
second: float or NoneType, default None: second of the minute
DofY: float or NoneType, default None: day of the year (January 1 = 1)

Returns:

t_date: float: date in decimal-year format

References

[1]

Dershowitz, N. and E.M. Reingold. 2008. Calendrical Calculations. Cambridge: Cambridge University Press.

SMBcorr.time.convert_julian(JD, **kwargs)[source]

Converts from Julian day to calendar date and time

Parameters:

JD: float

Julian Day (days since 01-01-4713 BCE at 12:00:00)

astype: str or NoneType, default None

convert output to variable type

format: str, default ‘dict’

format of output variables

'dict': dictionary with variable keys

'tuple': tuple in most-to-least-significant order

'zip': aggregated variable sets

Returns:

year: float: calendar year
month: float: calendar month
day: float: day of the month
hour: float: hour of the day
minute: float: minute of the hour
second: float: second of the minute

References

[1]

“Numerical Recipes in C”, by William H. Press, Brian P. Flannery, Saul A. Teukolsky, and William T. Vetterling. Cambridge University Press, 1988 (second printing).

[2]

Hatcher, D. A., “Simple Formulae for Julian Day Numbers and Calendar Dates”, Quarterly Journal of the Royal Astronomical Society, 25(1), 1984.

SMBcorr.time.count_leap_seconds(GPS_Time, truncate=True)[source]

Counts the number of leap seconds between a given GPS time and UTC

Parameters:

GPS_Time: float: seconds since January 6, 1980 at 00:00:00
truncate: bool, default True: Reduce list of leap seconds to positive GPS times

Returns:

n_leaps: float: number of elapsed leap seconds

SMBcorr.time.get_leap_seconds(truncate=True)[source]

Gets a list of GPS times for when leap seconds occurred

Parameters:

truncate: bool, default True: Reduce list of leap seconds to positive GPS times

Returns:

GPS time: float: GPS seconds when leap seconds occurred

SMBcorr.time.update_leap_seconds(timeout=20, verbose=False, mode=509)[source]